Driving assist apparatus of vehicle

ABSTRACT

A driving assist apparatus of a vehicle of the invention predicts, as a predicted minimum left turn radius, a curvature radius of a moving route of the vehicle at a point where a curvature radius of the moving route is predicted to become smallest when the vehicle turns left, and sets a route curved along an arc having the predicted minimum left turn radius as a predicted moving route predicted for the vehicle to move. The apparatus predicts, as a predetermined minimum right turn radius, the curvature radius of the moving route of the vehicle at the point where the curvature radius is predicted to become smallest when the vehicle turns right, and sets the route curved along the arc having the predicted minimum right turn radius as the predicted moving route.

BACKGROUND Field

The invention relates to a driving assist apparatus of a vehicle forperforming an attention operation to a driver of the vehicle as an ownvehicle when moving objects such as walking persons and other vehiclesexisting around the own vehicle may cross a moving route of the ownvehicle.

Description of the Related Art

There is known a driving assist apparatus of a vehicle for performing anattention operation to a driver of the vehicle as an own vehicle whenanother vehicle moves into a predetermined range defined around the ownvehicle (see JP 5435172 B). Hereinafter, this driving assist apparatuswill be referred to as “the conventional apparatus”.

The conventional apparatus is configured to set the predetermined range,assuming that that the own vehicle moves straight backward. With thisconfiguration, the other vehicle may cross a moving route of the ownvehicle when the own vehicle turns left or right even though the othervehicle does not enter into the predetermined range.

In this case, the attention operation to the driver should be performed.However, the conventional apparatus does not perform the attentionoperation to the driver since the other vehicle does not enter into thepredetermined range.

The invention has been made for solving a problem described above. Anobject of the invention is to provide a driving assist apparatus of avehicle for appropriately perform the attention operation to the driverwhen the moving objects such as the walking persons and the othervehicles may cross the moving route of the own vehicle while the ownvehicle turns left or right.

SUMMARY

The driving assist apparatus of the vehicle (V) according to theinvention comprises at least one sensor (16L, 16R) and an electroniccontrol unit (10, 20, 30). The sensor (16L, 16R) detects a moving object(A to J) existing around the vehicle (V). The electronic control unit(10, 20, 30) performs an attention operation to a driver of the vehicle(V). Hereinafter, the driving assist apparatus according to theinvention will be referred to as “the invention apparatus”.

The electronic control unit (10, 20, 30) is configured to set apredicted moving route (fL, fR) corresponding to a route predicted forthe vehicle (V) to move (see a process of a step 1120 of FIG. 11). Theelectronic control unit (10, 20, 30) is configured to perform theattention operation (see processes of a step 1235 of FIG. 12 and a step1750 of FIG. 17) when a time (t1, t2) predicted for the vehicle (V) toreach a point where the moving object (A to J) crosses the predictedmoving route (fL, fR) is smaller than or equal to a threshold time(t1th, t2th) (see determinations “Yes” at a step 1230 of FIG. 12 and astep 1740 of FIG. 17),

When the vehicle (V) turns left, the electronic control unit (10, 20,30) is configured to predict, as a predicted minimum left turn radius(R), a curvature radius (Rest1) of a moving route of the vehicle (V) ata point where the curvature radius (Rest1) of the moving route ispredicted to become smallest after the vehicle (V) starts to turn left(see a process of a step 1435 of FIG. 14) and to set a route curvedalong an arc having the predicted minimum left turn radius (R) as thepredicted moving route (fL, fR) (see the process of the step 1120 ofFIG. 11).

When the vehicle (V) turns right, the electronic control unit (10, 20,30) is configured to predict, as a predetermined minimum right turnradius (R), the curvature radius (Rest1) of the moving route of thevehicle (V) at the point where the curvature radius (Rest1) is predictedto become smallest after the vehicle (V) starts to turn right (see theprocess of the step 1435 of FIG. 14) and to set the route curved alongthe arc having the predicted minimum right turn radius (R) as thepredicted moving route (fL, fR) (see the process of the step 1120 ofFIG. 11).

Generally, when the driver turns the vehicle left or right, the driverfirst rotates a steering wheel of the vehicle to increase a steeringangle gradually. After the steering angle reaches a certain largesteering angle, the driver maintains the steering angle at the certainlarge steering angle. Thereafter, the driver rotates the steering wheelto decrease the steering angle gradually to zero and then, the driverends a left or right turning of the vehicle.

Therefore, the curvature radius of the moving route of the vehicledecreases gradually until the steering angle reaches the certain largesteering angle. When the steering angle reaches the certain largesteering angle, the curvature radius of the moving route of the vehiclebecomes smallest. Thus, immediately after the vehicle starts to turnleft or right, the curvature radius of the moving route of the vehicleis large. Thereafter, the curvature radius of the moving route of thevehicle decreases gradually. According to a study by the inventors ofthis application, the inventors have realized that the moving route ofthe vehicle predicted, using the curvature radius of the moving route ofthe vehicle (i.e., the smallest curvature radius) at a time of thesteering angle reaching the certain large steering angle is approximateto an actual moving route of the vehicle, compared with the moving routeof the vehicle predicted, using the curvature radius larger than thesmallest curvature radius.

The invention apparatus sets the predicted moving route, using thecurvature radius of the moving route of the vehicle at the point wherethe curvature radius of the moving route is predicted to become smallestafter the vehicle starts to turn left or right. Therefore, the predictedmoving route is approximate to the actual moving route of the vehicle.Thus, the attention operation to the driver can be appropriatelyperformed.

According to an aspect of the invention, when the vehicle (V) turnsleft, the electronic control unit (10, 20, 30) may be configured topresume that a yaw rate (Y) of the vehicle (V) increases by a changerate (ΔYsc) of the yaw rate (Y) of the vehicle (V) on a moment-to-momentbasis while the vehicle (V) turns left for predicting the predictedminimum left turn radius (R) (see processes of steps 1405, 1410, 1420and 1425 and the process of the step 1435 of FIG. 14). Further, when thevehicle (V) turns right, the electronic control unit (10, 20, 30) may beconfigured to presume that the yaw rate (Y) of the vehicle (V) increasesby the change rate (ΔYsc) of the yaw rate (Y) of the vehicle (V) on amoment-to-moment basis while the vehicle (V) turns right for predictingthe predicted minimum right turn radius (R) (see the processes of thesteps 1405, 1410, 1420, 1425 and 1435 of FIG. 14).

The change rate of the yaw rate of the vehicle correlates with a changerate of the curvature radius of the moving route of the vehicle.Therefore, the curvature radius of the moving route of the vehicle atthe point where the curvature radius is predicted to become smallest,can be accurately predicted by using the change rate of the yaw rate ofthe vehicle. The invention apparatus uses the change rate of the yawrate of the vehicle for predicting the point where the curvature radiusof the moving route of the vehicle is predicted to become smallest. As aresult, the moving route of the vehicle can be accurately predicted.Thus, the attention operation to the driver can be appropriatelyperformed.

According to another aspect of the invention, after the curvature radiusbecomes smallest while the vehicle (V) turns left (see a determination“No” at a step 1345 of FIG. 13), the electronic control unit (10, 20,30) may be configured to set, as the predicted minimum left turn radius(R), the curvature radius at a point where the curvature radius becomessmallest (see processes of steps 1515, 1520, 1540 and 1545 of FIG. 15).Further, after the curvature radius becomes smallest while the vehicle(V) turns right (see a determination “No” at the step 1345 of FIG. 13),the electronic control unit (10, 20, 30) may be configured to set, asthe predicted minimum right turn radius (R), the curvature radius at thepoint where the curvature radius becomes smallest (see the processes ofthe steps 1515, 1520, 1540 and 1545 of FIG. 15).

As described above, generally, when the driver turns the vehicle left orright, the driver maintains the steering angle of the steering wheel ofthe vehicle at the certain large steering angle for a while after thesteering angle reaches the certain large steering angle. Thereafter, thedriver decreases the steering angle gradually to zero and as a result,the driver ends the left or right turning of the vehicle.

Therefore, after the steering angle reaches the certain large steeringangle and thus, the curvature radius of the moving route of the vehiclebecomes smallest, the curvature radius of the moving route of thevehicle increases gradually. As described above, according to the studyof the inventors of this application, it has been realized that themoving route of the vehicle predicted, using the minimum left or rightturn curvature radius corresponding to the curvature radius of themoving route of the vehicle at the time of the steering angle reachingthe certain large steering angle, is approximate to the actual movingroute of the vehicle, compared with the moving route predicted, usingthe curvature radius larger than the minimum curvature radius.

After the curvature radius of the moving route of the vehicle reachesthe minimum curvature radius, the invention apparatus sets, as theminimum left or right turn radius, the minimum curvature radius vehicleand sets the predicted moving route, using the thus-set minimum left orright radius. Therefore, the thus-set predicted moving route isapproximate to the actual moving route of the vehicle. Thus, theattention operation to the driver can be appropriately performed.

According to further another aspect of the invention, the vehicle (V)may comprise at least one left direction blinker activated forindicating that the vehicle (V) is to turn left and at least one rightdirection blinker activated for indicating that the vehicle (V) is toturn right.

The electronic control unit (10, 20, 30) may be configured to predictthat the vehicle (V) turns left when a speed (SPD) of the vehicle (V) iswithin a predetermined speed range (Rspd1) and the left directionblinker is activated (see a determination “Yes” at a step 610 of FIG.16).

Further, the electronic control unit (10, 20, 30) may be configured topredict that the vehicle (V) turns right when the speed (SPD) of thevehicle (V) is within the predetermined speed range (Rspd1) and theright direction blinker is activated (see a determination “Yes” at astep 655 of FIG. 6).

When the driver starts to turn the vehicle left or right, the drivergenerally activates the left or right direction blinker after the driverdecelerates the vehicle to decrease the speed of the vehicle to a speedsuitable to start to turn the vehicle left or right. Otherwise, thedriver generally decelerates the vehicle to decrease the speed of thevehicle to the speed suitable to start to turn the vehicle left or rightafter the driver activates the left or right direction blinker.Otherwise, the driver generally activates the left or right directionblinker and decelerates the vehicle to decrease the speed of the vehicleto the speed suitable to start to turn the vehicle left or right. Theinvention apparatus determines whether the vehicle is to turn left orright on the basis of the speed of the vehicle and the activated stateof the left or right direction blinker. Therefore, the inventionapparatus can determine accurately whether the vehicle is to turn leftor right.

According to further another aspect of the invention, when the vehicle(V) comprises the left and right direction blinkers, the electroniccontrol unit (10, 20, 30) may be configured to determine whether thevehicle (V) turns left or right on the basis of a vehicle informationincluding activation states of the left and right direction blinkers(see processes of steps 635 and 680 of FIG. 6).

The driver generally activates the left direction blinker when thedriver turns the vehicle left. Similarly, when the driver turns thevehicle right, the driver generally activates the right directionblinker. The invention apparatus determines whether the vehicle turnsleft or right on the basis of the activated state of the left or rightdirection blinker. Therefore, the invention apparatus can determineaccurately whether the vehicle turns left or right.

According to further another aspect of the invention, the vehicleinformation may include at least one of a yaw rate (Y, Ys) of thevehicle (V), a speed (SPD) of the vehicle (V), a longitudinalacceleration (Gx) of the vehicle (V), an operation amount (AP) of anacceleration pedal (11 a) of the vehicle (V), a lateral acceleration(Gy) of the vehicle (V) and a steering angle (θsw) of a steering wheel(14 a) of the vehicle (V).

Values of parameters such as the yaw rate, the speed, the longitudinalacceleration, the operation amount of the acceleration pedal, thelateral acceleration and the steering angle of the steering wheel of thevehicle acquired when the vehicle turns left, are different from thoseacquired when the vehicle turns right. In addition, the values of theparameters acquired when the vehicle turns left or right, are differentfrom those acquired when the vehicle moves straight.

The invention apparatus according to this aspect employs, as the vehicleinformation used for determining whether the vehicle turns left orright, at least one of the yaw rate, the speed, the longitudinalacceleration, the operation amount of the acceleration pedal, thelateral acceleration and the steering angle of the steering wheel of thevehicle. Therefore, the invention apparatus can determine appropriatelywhether the vehicle turns left or right.

In the above description, for facilitating understanding of the presentinvention, elements of the present invention corresponding to elementsof an embodiment described later are denoted by reference symbols usedin the description of the embodiment accompanied with parentheses.However, the elements of the present invention are not limited to theelements of the embodiment defined by the reference symbols. The otherobjects, features and accompanied advantages of the present inventioncan be easily understood from the description of the embodiment of thepresent invention along with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view for showing a first embodiment apparatus correspondingto a driving assist apparatus of a vehicle according to a firstembodiment of the invention and the vehicle to which the firstembodiment apparatus is applied.

FIG. 2 is a view for showing the vehicle shown in FIG. 1.

FIG. 3 is a view for showing the vehicle which is to start to turn leftor right at an intersection.

FIG. 4 is a view for showing the vehicle which turns right at theintersection.

FIG. 5 is a view used for describing an attention operation to a driverof the vehicle performed by the first embodiment apparatus.

FIG. 6 is a view for showing a flowchart of a routine executed by a CPUof a driving assist ECU of the first embodiment apparatus.

FIG. 7 is a view for showing a flowchart of a routine executed by theCPU.

FIG. 8 is a view for showing a flowchart of a routine executed by theCPU.

FIG. 9 is a view for showing a flowchart of a routine executed by theCPU.

FIG. 10 is a view for showing a flowchart of a routine executed by theCPU.

FIG. 11 is a view for showing a flowchart of a routine executed by theCPU.

FIG. 12 is a view for showing a flowchart of a routine executed by theCPU.

FIG. 13 is a view for showing a flowchart of a routine executed by a CPUof a driving assist ECU of a modified apparatus corresponding to adriving assist apparatus of the vehicle according to a modifiedembodiment of the first embodiment.

FIG. 14 is a view for showing a flowchart of a routine executed by theCPU of the modified apparatus.

FIG. 15 is a view for showing a flowchart of a routine executed by theCPU of the modified apparatus.

FIG. 16 is a view used for describing the attention operation to thedriver performed by a second embodiment apparatus corresponding to adriving assist apparatus of the vehicle according to a second embodimentof the invention.

FIG. 17 is a view for showing a flowchart of a routine executed by a CPUof a driving assist ECU of the second embodiment apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

Below, a driving assist apparatus of a vehicle according to a firstembodiment of the invention will be described with reference to thedrawings. The driving assist apparatus according to the first embodimentis applied to a vehicle V shown in FIG. 1. The driving assist apparatusaccording to the first embodiment includes a driving assist ECU 10, adisplay ECU 20 and an alert ECU 30. Hereinafter, the driving assistapparatus according to the first embodiment will be referred to as “thefirst embodiment apparatus” and the vehicle V to which the firstembodiment apparatus is applied, will be referred to as “the own vehicleV”.

Each of the ECUs 10, 20 and 30 is an electronic control unit includingas a main component, a micro-computer including a CPU, a ROM, a RAM, aninterface and the like. The CPU of each of the ECUs 10, 20 and 30accomplishes various functions described later by executing instructionsor routines stored in a memory such as the ROM thereof. In this regard,two or all of the ECUs 10, 20 and 30 may be integrated into one ECU.

The driving assist ECU 10, the display ECU 20 and the alert ECU 30 areelectrically connected to each other so as to communicate with, i.e.,receive data from and send data to each other via a communication/sensorsystem CAN (i.e., Controller Area Network) 90.

The own vehicle V includes a blinker lever (not shown). The blinkerlever is provided on a steering column and is operated by a driver ofthe own vehicle V. Each of states of blinkers (not shown) provided on aleft-front end portion and a left-rear end portion of the own vehicle V,respectively changes from a non-blinking state (i.e., a non-activatedstate) to a blinking state (i.e., an activated state) by the driveroperating the blinker lever from a neutral position to one sideposition. Hereinafter, the blinkers provided on the left-front andleft-rear end portions of the own vehicle V will be referred to as “theleft direction blinkers”. The state of each of the left directionblinkers changes from the blinking state to the non-blinking state bythe driver returning the blinker lever to the neutral position.

On the other hand, each of states of blinkers (not shown) provided on aright-front end portion and a right-rear end portion of the own vehicleV, respectively changes from the non-blinking state (i.e., thenon-activated state) to the blinking state (i.e., the activated state)by the driver operating the blinker lever from the neutral position tothe other side position. Hereinafter, the blinkers provided on theright-front and right-rear end portions of the own vehicle V will bereferred to as “the right direction blinkers”. The state of each of theright direction blinkers changes from the blinking state to thenon-blinking state by the driver returning the blinker lever to theneutral position.

The own vehicle V includes an accelerator pedal operation amount sensor11, a brake pedal operation amount sensor 12, a left direction blinkersensor 13L, a right direction blinker sensor 13R, a steering anglesensor 14, a vehicle speed sensor 15, a left-front radar sensor 16L, aright-front radar sensor 16R, a yaw rate sensor 17, a longitudinaldirection acceleration sensor 18 and a lateral direction accelerationsensor 19. These sensors 11, 12, 13L, 13R, 14, 15, 16L, 16R, 17, 18 and19 are electrically connected to the driving assist ECU 10.

The acceleration pedal operation amount sensor 11 detects anacceleration pedal operation amount corresponding to an operation amountAP [%] of an acceleration pedal 11 a and outputs a signal indicating theacceleration pedal operation amount AP to the driving assist ECU 10 asown vehicle information. The driving assist ECU 10 acquires theacceleration pedal operation amount AP on the basis of the signalreceived from the acceleration pedal operation amount sensor 11 eachtime a predetermined calculation time Tcal elapses.

The brake pedal operation amount sensor 12 detects a brake pedaloperation amount corresponding to an operation amount BP [%] of a brakepedal 12 a and outputs a signal indicating the brake pedal operationamount BP to the driving assist ECU 10 as the own vehicle information.The driving assist ECU 10 acquires the brake pedal operation amount BPon the basis of the signal received from the brake pedal operationamount sensor 12 each time the predetermined calculation time Tcalelapses.

The left direction blinker sensor 13L outputs a left-turn signalindicating that the state of each of the left direction blinkers is theblinking state to the driving assist ECU 10 as the own vehicleinformation when the state of each of the left direction blinkerschanges from the non-blinking state to the blinking state. On the otherhand, when the state of each of the left direction blinkers changes fromthe blinking state to the non-blinking state, the left direction blinkersensor 13L outputs a non-left-turn signal indicating that the state ofeach of the left direction blinkers is the non-blinking state to thedriving assist ECU 10 as the own vehicle information. The driving assistECU 10 acquires the states of the left direction blinkers on the basisof the left-turn and non-left-turn signals received from the leftdirection blinker sensor 13L each time the predetermined calculationtime Tcal elapses.

The right direction blinker sensor 13R outputs a right-turn signalindicating that the state of each of the right direction blinkers is theblinking state to the driving assist ECU 10 as the own vehicleinformation when the state of each of the right direction blinkerschanges from the non-blinking state to the blinking state. On the otherhand, when the state of each of the right direction blinkers changesfrom the blinking state to the non-blinking state, the right directionblinker sensor 13R outputs a non-right-turn signal indicating that thestate of each of the right direction blinkers is the non-blinking stateto the driving assist ECU 10 as the own vehicle information. The drivingassist ECU 10 acquires the states of the right blinkers on the basis ofthe right-turn and non-right-turn signals received from the rightdirection blinker sensor 13R each time the predetermined calculationtime Tcal elapses.

The steering angle sensor 14 detects a steering angle corresponding arotation angle θsw [°] of a steering wheel 14 a with respect to a baseposition corresponding to a rotation position of the steering wheel 14 alocated for causing the own vehicle V to move straight and outputs asignal indicating the steering angle θsw to the driving assist ECU 10 asthe own vehicle information. The driving assist ECU 10 acquires thesteering angle θsw on the basis of the signal received from the steeringangle sensor 14 each time the predetermined calculation time Tcalelapses. In this case, the steering angle θsw is larger than zero whenthe steering wheel 14 a is rotated to cause the own vehicle V to turnleft. On the other hand, the steering angle θsw is smaller than zerowhen the steering wheel 14 a is rotated to cause the own vehicle V toturn right.

The vehicle speed sensor 15 detects a vehicle speed corresponding to aspeed SPD [km/h] of the own vehicle V and outputs a signal indicatingthe speed SPD to the driving assist ECU 10 as the own vehicleinformation. The driving assist ECU 10 acquires the speed SPD on thebasis of the signal received from the vehicle speed sensor 15 each timethe predetermined calculation time Tcal elapses. Hereinafter, the speedSPD will be referred to as “the vehicle speed SPD”.

As shown in FIG. 2, the left front radar sensor 16L is provided on aleft end of a front end portion of the own vehicle V. The left frontradar sensor 16L transmits a radio wave ahead of the own vehicle Vdiagonally left. When an object such as a walking person and a vehicleother than the own vehicle V exists within a reachable range of theradio wave transmitted from the left front radar sensor 16L, thetransmitted radio wave is reflected by the object. The left front radarsensor 16L receives the reflected radio wave. The left front radarsensor 16L outputs signals indicating the transmitted radio wave and thereflected radio wave, respectively to the driving assist ECU 10.Hereinafter, the vehicle other than the own vehicle will be referred toas “the other vehicle”.

The driving assist ECU 10 determines whether the object exists aroundthe own vehicle V on the basis of the signals received from the leftfront radar sensor 16L each time the predetermined calculation time Tcalelapses. When the object exists, the driving assist ECU 10 calculates adistance between the own vehicle V and the object and an orientation ofthe object with respect to the own vehicle V. The driving assist ECU 10acquires information on a position of the object with respect to the ownvehicle V, a moving direction of the object, a moving speed of theobject and the like as object information.

Also, as shown in FIG. 2, the right front radar sensor 16R is providedon a right end of a front end portion of the own vehicle V. The rightfront radar sensor 16R transmits a radio wave ahead of the own vehicle Vdiagonally right. When the object such as the walking person and theother vehicle exists within the reachable range of the radio wavetransmitted from the right front radar sensor 16R, the transmitted radiowave is reflected by the object. The right front radar sensor 16Rreceives the reflected radio wave. The right front radar sensor 16Routputs signals indicating the transmitted radio wave and the reflectedradio wave, respectively to the driving assist ECU 10.

The driving assist ECU 10 determines whether the object exists aroundthe own vehicle V on the basis of the signals received from the rightfront radar sensor 16R each time the predetermined calculation time Tcalelapses. When the object exists, the driving assist ECU 10 calculatesthe distance between the own vehicle V and the object and theorientation of the object with respect to the own vehicle V. The drivingassist ECU 10 acquires the information on the position of the objectwith respect to the own vehicle V, the moving direction of the object,the moving speed of the object and the like as the object information.

It should be noted that when the left and right front radar sensors 16Land 16R output the signals indicating the radio waves reflected by thesame object, respectively, the driving assist ECU 10 acquires the objectinformation on the same object on the basis of the signals received fromthe left and right front radar sensors 16L and 16R, respectively.

With reference to FIG. 1, the yaw rate sensor 17 detects a yaw ratecorresponding to an angle speed Y [°/sec] of the own vehicle V andoutputs a signal indicating the yaw rate Y to the driving assist ECU 10as the own vehicle information. The driving assist ECU 10 acquires theyaw rate Yon the basis of the signal received from the yaw rate sensor17 each time the predetermined calculation time Tcal elapses. When theown vehicle V turns left, the acquired yaw rate Y is larger than zero.On the other hand, when the own vehicle V turns right, the acquired yawrate Y is smaller than zero. When the own vehicle V moves straight, theacquired yaw rate Y is zero.

The longitudinal direction acceleration sensor 18 detects a longitudinalacceleration Gx [m/s²] of the own vehicle V and outputs a signalindicating the longitudinal acceleration Gx to the driving assist ECU 10as the own vehicle information. The driving assist ECU 10 acquires thelongitudinal acceleration Gx on the basis of the signal received fromthe longitudinal direction acceleration sensor 18 each time thepredetermined calculation time Tcal elapses. When the own vehicle V isaccelerated, the acquired longitudinal acceleration Gx is larger thanzero. On the other hand, when the own vehicle V is decelerated, theacquired longitudinal acceleration Gx is smaller than zero. When the ownvehicle V is not accelerated nor decelerated, the acquired longitudinalacceleration Gx is zero.

The lateral direction acceleration sensor 19 detects a lateralacceleration Gy [m/s²] of the own vehicle V and outputs a signalindicating the lateral acceleration Gy to the driving assist ECU 10 asthe own vehicle information. The driving assist ECU 10 acquires thelateral acceleration Gy on the basis of the signal received from thelateral direction acceleration sensor 19 each time the predeterminedcalculation time Tcal elapses. When the own vehicle V turns left, theacquired lateral acceleration Gy is larger than zero. On the other hand,when the own vehicle V turns right, the acquired lateral acceleration Gyis smaller than zero. When the own vehicle V moves straight, theacquired lateral acceleration Gy is zero.

The own vehicle information indicates a driving state of the own vehicleV acquired by the aforementioned various sensors mounted on the ownvehicle V. The driving assist ECU 10 stores the acquired own vehicleinformation and object information in the RAM.

When the object may cross a predicted vehicle moving route correspondingto a route along which the own vehicle V is predicted to move asdescribed later, the driving assist ECU 10 sends a request signal forrequesting to perform an attention operation for drawing an attention ofthe driver of the own vehicle V, to the display ECU 20 and the alert ECU30.

A display device 21 shown in FIG. 1 is a display device provided at aposition which the driver of the own vehicle V can see, for example, ata meter cluster panel. The display device 21 is electrically connectedto the display ECU 20. The display ECU 20 sends a command signal to thedisplay device 21 when the display ECU 20 receives the request signalfrom the driving assist ECU 10. The display device 21 performs theattention operation for drawing the driver's attention when the displaydevice 21 receives the command signal from the display ECU 20. Thedisplay device 21 may be a head-up display or a center display or thelike.

A buzzer 31 shown in FIG. 1 is electrically connected to the alert ECU30. The alert ECU 30 sends a command signal to the buzzer 31 when thealert ECU 30 receives the request signal from the driving assist ECU 10.The buzzer 31 generates an alert sound for drawing the driver'sattention as the attention operation. The attention operation to thedriver may be performed by one of the display device 21 and the buzzer31.

<Summary of Operation of First Embodiment Apparatus>

Below, a summary of an operation of the first embodiment apparatus willbe described. In particular, the operation of the first embodimentapparatus performed when the own vehicle V turns left or right at aturning position. It should be noted that the turning position is anintersection or a parking area of a building or a road next to anentrance of the parking area or the like. Below, the operation of thefirst embodiment apparatus will be described when the turning positionis the intersection.

When the driver turns the own vehicle V left or right at theintersection, the driver causes the own vehicle V to move into theintersection while the driver decreases the vehicle speed SPD of the ownvehicle V. Thereafter, the driver rotates the steering wheel 14 a toturn the own vehicle V left or right. Finally, the driver returns therotation position of the steering wheel 14 a to the base position andterminates a left or right turning of the own vehicle V.

In this regard, the object such as the walking person and the othervehicle may cross the predicted vehicle moving route of the own vehicleV. When the own vehicle V turns left or right in the intersection, thefirst embodiment apparatus acquires the predicted vehicle moving routeof the own vehicle V as described later assuming that the predictedvehicle moving route has an arc shape.

Further, the first embodiment apparatus calculates a total turn anglecorresponding to a total angle θtotal of the turning of the own vehicleV in the intersection. Then, the first embodiment apparatus calculates,on the basis of the total turn angle θtotal, a turn remaining anglecorresponding to an angle that the own vehicle V should turn until theown vehicle V completes the left or right turning. Then, the firstembodiment apparatus calculates an effective length of the predictedvehicle moving route on the basis of the turn remaining angle. When theobject may cross a portion of the predicted vehicle moving routecorresponding to the calculated effective length, the first embodimentapparatus performs the attention operation to the driver, using thedisplay device 21 and the buzzer 31.

In particular, the first embodiment apparatus determines whether thedriver has an attempt to turn the own vehicle V left or right, in otherwords, whether the own vehicle V is not substantially turning left orright, but the own vehicle V is set to turn left or right each time thepredetermined calculation time Tcal elapses.

<Left Turn Waiting Condition>

When a left turn waiting condition is satisfied, the first embodimentapparatus determines that the own vehicle V is set to turn left. Theleft turn waiting condition is satisfied when at least one of conditionsLW1 to LW3 described below is satisfied.

A waiting vehicle speed range Rspd1 described below is a range of thegeneral vehicle speed of the own vehicle V when the own vehicle V is setto turn left. In the first embodiment, a first vehicle speed SPD1corresponding to a lower limit of the range Rspd1 is 0 km/h. A secondvehicle speed SPD2 corresponding to an upper limit of the range Rspd1 is20 km/h. The same is applied to the right turning of the own vehicle V.

Condition LW1: The state of each of the left direction blinkers changesfrom the non-blinking state to the blinking state while the vehiclespeed SPD of the own vehicle V is within the waiting vehicle speed rangeRspd1.

Condition LW2: The vehicle speed SPD changes from the vehicle speed SPDout of the waiting vehicle speed range Rspd1 to the vehicle speed SPDwithin the waiting vehicle speed range Rspd1 while each of the leftdirection blinkers is in the blinking state.

Condition LW3: The vehicle speed SPD changes from the vehicle speed SPDout of the waiting vehicle speed range Rspd1 to the vehicle speed SPDwithin the waiting vehicle speed range Rspd1 and the state of each ofthe left direction blinkers changes from the non-blinking state to theblinking state.

<Right Turn Waiting Condition>

When a right turn waiting condition is satisfied, the first embodimentapparatus determines that the own vehicle V is set to turn right. Theright turn waiting condition is satisfied when at least one ofconditions RW1 to RW3 described below is satisfied.

Condition RW1: The state of each of the right direction blinkers changesfrom the non-blinking state to the blinking state while the vehiclespeed SPD of the own vehicle V is within the waiting vehicle speed rangeRspd1.

Condition RW2: The vehicle speed SPD changes from the vehicle speed SPDout of the waiting vehicle speed range Rspd1 to the vehicle speed SPDwithin the waiting vehicle speed range Rspd1 while each of the rightdirection blinkers is in the blinking state.

Condition RW3: The vehicle speed SPD changes from the vehicle speed SPDout of the waiting vehicle speed range Rspd1 to the vehicle speed SPDwithin the waiting vehicle speed range Rspd1 and the state of each ofthe right direction blinkers changes from the non-blinking state to theblinking state.

In the following description, when a symbol “e” is a parameter and asymbol “n” is a calculation cycle, a term “e(n)” means the parameteracquired or predicted at the calculation cycle “n”. When the left orright turn waiting condition is satisfied, that is, when the own vehicleV is determined to be set to turn left or right, the calculation cycle“n” is zero.

A vehicle base point corresponding to a point O(n) shown in FIG. 2 is acenter point in a width of the own vehicle V adjacent to the front endportion of the own vehicle V.

In addition, the first embodiment apparatus calculates the total turnangle θtotal(n) which the own vehicle V has turned from the vehicle basepoint O(0) to the vehicle base point O(n). The vehicle base point O(0)is the vehicle base point at the calculation cycle “0” as shown by adashed line in FIG. 4. The vehicle base point O(n) is the vehicle basepoint for the calculation cycle “n” as shown by a solid line in FIG. 4.The first embodiment apparatus previously sets a turn end angle θendwhich the own vehicle V generally needs to turn until the own vehicle Vcompletes the left or right turning after the own vehicle V starts toturn left or right. In the first embodiment, the turn end angle θend isset to 90°. When the total turn angle θtotal(n) becomes larger than theturn end angle θend or when the state of each of the left directionblinkers or the state of each of the right direction blinkers changesfrom the blinking state to the non-blinking state before the total turnangle θtotal(n) becomes larger than the turn end angle θend, the firstembodiment apparatus determines that the own vehicle V completes theleft or right turning.

Generally, while the own vehicle V is set to turn left or right, thevehicle speed SPD of the own vehicle V continues to be within thewaiting vehicle speed range Rspd1 and the left or right directionblinkers continue to blink. Therefore, the conditions LW1 to LW3 or theconditions RW1 to RW3 are not satisfied until the own vehicle Vcompletes the left or right turning after the left or right turn waitingcondition is once satisfied. Thus, the left or right turn waitingcondition is not satisfied after the left or right turn waitingcondition is once satisfied.

The first embodiment apparatus determines that the own vehicle V is setto turn left or right until a left or right turn start conditiondescribed later is satisfied after the left or right turn waitingcondition is once satisfied as far as the left direction blinkers or theright direction blinkers blink.

Except for an exceptional case that the driver performs an operation forreturning the state of each of the left or right direction blinkers tothe non-blinking state while the own vehicle V turns left or right, theleft or right turn waiting condition is satisfied once at oneintersection.

<Left Turn Start Determination>

While the left direction blinkers are blinking, that is, the drivershows an intention to cause the own vehicle V to turn left after thefirst embodiment apparatus determines that the own vehicle V is set toturn left, that is, the left turn waiting condition is satisfied, thefirst embodiment apparatus determines whether the own vehicle V isactually turning left, that is, the own vehicle V is in a left turnstate each time the predetermined calculation time Tcal elapses.

The first embodiment apparatus determines that the own vehicle V startsto turn left when the left turn start condition described below is firstsatisfied while the left direction blinkers are blinking after the leftturn waiting condition is satisfied. The left turn start condition issatisfied when conditions LS1 to LS6 described below are all satisfied.

Turning vehicle speed range Rspd2 described below is a general vehiclespeed range of the own vehicle V turning left. A lower limit vehiclespeed SPDL of the range Rspd2 is larger than the first vehicle speedSPD1 and in the first embodiment, is 5 km/h. An upper limit vehiclespeed SPDU of the range Rspd2 is smaller than or equal to the secondvehicle speed SPD2 and in the first embodiment, is 20 km/h.

Condition LS1: The vehicle speed SPD is within the turning vehicle speedrange Rspd2.

Condition LS2: The longitudinal acceleration Gx is smaller than anacceleration threshold Gxa when the longitudinal acceleration Gx islarger than or equal to zero or an absolute value of the longitudinalacceleration Gx is smaller than a deceleration threshold Gxd when thelongitudinal acceleration Gx is smaller than zero. In the firstembodiment, the threshold Gxa is 4 m/s² and the threshold Gxd is 4 m/s².

Condition LS3: The acceleration pedal operation amount AP is smallerthan an operation amount threshold APth. In the first embodiment, thethreshold APth is 2%.

Condition LS4: The yaw rate Y is larger than a left-or-right turndetermination threshold Yth when the yaw rate Y is larger than zero. Thethreshold Yth is a turn start index threshold and in the firstembodiment, 8°/sec.

Condition LS5: The lateral acceleration Gy is larger than aleft-or-right turn determination threshold Gyth when the lateralacceleration Gy is larger than zero. In the first embodiment, thethreshold Gyth is 3 m/s².

Condition LS6: The steering angle θsw is larger than a left-or-rightturn determination threshold θswth when the steering angle θsw is largerthan zero. In this embodiment, the threshold θswth is 45°.

When the left turn start condition continues to be satisfied after theleft turn start condition is first satisfied, the first embodimentapparatus determines that the own vehicle V is in the left turn state,that is, the own vehicle V is actually turning left.

For example, when the own vehicle V stops temporarily around a centerarea of the intersection to wait for the oncoming vehicle, the walkingperson and the like to pass the intersection after the own vehicle Vstarts to turn left, the left turn start condition becomes unsatisfied.In this regard, the driver continues to cause the left directionblinkers to blink when the own vehicle V stops temporarily in the middleof the left turning.

Accordingly, the first embodiment apparatus determines that the ownvehicle V is in the left turn state when the left direction blinkers areblinking even though the left turn start condition becomes unsatisfiedafter the left turn start condition is satisfied.

When the state of each of the left direction blinkers becomes thenon-blinking state after the left turn start condition is satisfied orwhen the total turn angle θtotal becomes larger than the turn end angleθend after the left turn start condition is satisfied, the firstembodiment apparatus determines that the own vehicle V completes theleft turning.

Hereinafter, a state that the own vehicle V is determined to be set toturn left, will be referred to as “the left turn waiting state L1”. Astate that the own vehicle V is determined to be turning left at theintersection, will be referred to as “the left turn state L2”.

<Right Turn Start Determination>

While the right turn blinkers are blinking, that is, the driver shows anintention to cause the own vehicle V to turn right after the firstembodiment apparatus determines that the own vehicle V is set to turnright, that is, the right turn waiting condition is satisfied, the firstembodiment apparatus determines whether the own vehicle V is actuallyturning right, that is, the own vehicle V is in a right turn state eachtime the predetermined calculation time Tcal elapses.

The first embodiment apparatus determines that the own vehicle V startsto turn right when the right turn start condition described below isfirst satisfied while the right direction blinkers are blinking afterthe right turn waiting condition is satisfied. The right turn startcondition is satisfied when conditions RS1 to RS6 described below areall satisfied.

Condition RS1: The vehicle speed SPD is within the turning vehicle speedrange Rspd2.

Condition RS2: The longitudinal acceleration Gx is smaller than theacceleration threshold Gxa when the longitudinal acceleration Gx islarger than or equal to zero or the absolute value of the longitudinalacceleration Gx is smaller than the deceleration threshold Gxd when thelongitudinal acceleration Gx is smaller than zero.

Condition RS3: The acceleration pedal operation amount AP is smallerthan the operation amount threshold APth.

Condition RS4: An absolute value of the yaw rate Y is larger than theleft-or-right turn determination threshold Yth when the yaw rate Y issmaller than zero.

Condition RS5: An absolute value of the lateral acceleration Gy islarger than the left-or-right turn determination threshold Gyth when thelateral acceleration Gy is smaller than zero.

Condition RS6: An absolute value of the steering angle θ is larger thanthe left-or-right turn determination threshold θswth when the steeringangle θsw is smaller than zero.

When the right turn start condition continues to be satisfied after theright turn start condition is first satisfied, the first embodimentapparatus determines that the own vehicle V is in the right turn state.

Similar to a case that the own vehicle V turns left, when the ownvehicle V stops temporarily around the center area of the intersectionto wait for the oncoming vehicle, the walking person and the like topass the intersection after the own vehicle V starts to turn right, theright turn start condition becomes unsatisfied. In this regard, thedriver continues to cause the right direction blinkers to blink when theown vehicle V stops temporarily in the middle of the right turning.

Accordingly, the first embodiment apparatus determines that the ownvehicle V is in the right turn state when the right turn blinkers areblinking even though the right turn start condition becomes unsatisfiedafter the right turn start condition is satisfied.

When the state of each of the right direction blinkers becomes thenon-blinking state after the right turn start condition is satisfied orwhen the total turn angle θtotal becomes larger than the turn end angleθend after the right turn start condition is satisfied, the firstembodiment apparatus determines that the own vehicle V completes theright turning.

Hereinafter, a state that the own vehicle V is determined to be set toturn right, will be referred to as “the right turn waiting state R1”. Astate that the own vehicle V is determined to be turning right at theintersection, will be referred to as “the right turn state R2.”

<Calculation of Smoothed Yaw Rate Ys>

The first embodiment apparatus uses the yaw rate Y of the own vehicle Vfor acquiring the predicted vehicle moving route as described later. Inthis regard, the yaw rate Y detected by the yaw rate sensor 17 isunstable. Accordingly, the first embodiment apparatus calculates asmoothed yaw rate Ys by smoothing the yaw rate Y each time thepredetermined calculation time Tcal elapses until the first embodimentapparatus makes a determination that the own vehicle V completes theleft turning after the left turn waiting condition is satisfied.Hereinafter, the determination that the own vehicle V completes the leftturning, will be referred to as “the left turn end determination” and aperiod until the first embodiment apparatus makes the left turn enddetermination, will be referred to as “the left turn period of the ownvehicle V. Also, the first embodiment apparatus calculates the smoothedyaw rate Ys by smoothing the yaw rate Y each time the predeterminedcalculation time Tcal elapses until the first embodiment apparatus makesa determination that the own vehicle V completes the right turning afterthe right turn waiting condition is satisfied. Hereinafter, thedetermination that the own vehicle V completes the right turning, willbe referred to as “the right turn end determination” and a period untilthe first embodiment apparatus makes the right turn end determination,will be referred to as “the right turn period of the own vehicle V.

In this regard, the yaw rate Y of the own vehicle V turning left ispositive and the yaw rate Y of the own vehicle V turning right isnegative. Therefore, a sign of the yaw rate Y of the own vehicle Vturning left is different from the sign of the yaw rate Y of the ownvehicle V turning right. Accordingly, the first embodiment apparatuscalculates the smoothed yaw rate Ys as described below. In the followingdescription, a symbol “M” is a predetermined positive integer.

The first embodiment apparatus calculates an average of the yaw ratesY(0) to Y(n) as the smoothed yaw rate Ys(n) as shown by an expression(1L) described below until the calculation cycle “n” reaches apredetermined calculation cycle “M” (n<M) after the left turn waitingcondition is satisfied.Ys(n)={Y(0)+ . . . +Y(n−1)+Y(n)}/(n+1)  (1L)

After the calculation cycle “n” reaches the predetermined calculationcycle “M” (n≤M), the first embodiment apparatus calculates an average ofthe consecutive yaw rates Y(n−(M−1) to Y(n) as the smoothed yaw rateYs(n) as shown by an expression (2L) described below.Ys(n)={Y(n−(M−1))+ . . . +Y(n−1)+Y(n)}/M  (2L)

On the other hand, after the right turn waiting condition is satisfied,the first embodiment apparatus calculates an average of the yaw ratesY(0) to Y(n) multiplied by “−1” as the smoothed yaw rate Ys(n) as shownby an expression (1R) described below until the calculation cycle “n”reaches the predetermined calculation cycle “M” (n<M).Ys(n)={(−Y(0))+ . . . +(−Y(n−1))+(−Y(n))}/(n+1)  (1R)

After the calculation cycle “n” reaches the predetermined calculationcycle “M” (n≤M), the first embodiment apparatus multiplies theconsecutive yaw rates Y(n−(M−1)) to Y(n) by “−1”, i.e., changes the signof the consecutive yaw rates Y(n−(M−1)) to Y(n), respectively. Then, thefirst embodiment apparatus calculates an average of the consecutive yawrates Y(n−(M−1)) to Y(n) each having the changed sign as the smoothedyaw rate Ys(n) as shown by an expression (2R) described below.Ys(n)={(−Y(n−(M−1)))+ . . . +(−Y(n−1))+(−Y(n))}/M  (2R)

As described above, the yaw rate of the own vehicle V is negative whenthe own vehicle V turns right. In the first embodiment, when the rightturn waiting condition is satisfied, the yaw rate Y is multiplied by“−1” such that the sign of the yaw rate Y is reversed. Then, the valuesof the yaw rates Y each having a reversed sign are smoothed, Thus, thesmoothed yaw rate Ys of the own vehicle V turning right can be equatedwith the smoothed yaw rate Ys of the own vehicle V turning left.

It should be noted that the smoothed yaw rate Ys of the own vehicle Vturning left may not be positive. Similarly, the smoothed yaw rate Ys ofthe own vehicle V turning right may not be positive. For example, whenthe own vehicle V turns right temporarily in the middle of the leftturning, i.e., the steering wheel 14 a is temporarily rotated to turnthe own vehicle V right in the middle of the left turning, the negativeyaw rate Y is detected at the calculation cycles during the temporaryright turning of the own vehicle V. In this case, the smoothed yaw rateYs calculated by the expression (1L) or (2L) may be negative.

Similarly, when the own vehicle V turns left temporarily in the middleof the right turning, i.e., the steering wheel 14 a is temporarilyrotated to turn the own vehicle V left in the middle of the rightturning, the positive yaw rate Y is detected at the calculation cyclesduring the temporary left turning of the own vehicle V. When thedetected positive yaw rate Y is multiplied by “−1”, the negative yawrate Y is obtained. In this case, the smoothed yaw rate Ys calculated bythe expression (1R) or (2R) may be negative.

Further, the own vehicle V may stop temporarily after the own vehicle Vis determined to start to turn left or right. In this case, the yaw rateY changes from a non-zero value to a zero value. In this case, thesmoothed yaw rate Ys calculated by any of the expressions (1L) to (2R)may be calculated as non-zero value departing from the zero value eventhough the actual yaw rate Y is the zero value. In this case, aninaccurate value is calculated.

Accordingly, when the yaw rate Y changes from the non-zero value to thezero value after the own vehicle V is determined to start to turn leftor right, the first embodiment apparatus sets the smoothed yaw rate Ysis to zero as shown by an expression (3) or (4) described below in placeof using any of the expressions (1L) to (2R).

In other words, when the own vehicle V is determined to start to turnleft or right at the calculation cycle “a” (1≤a) and then, the ownvehicle V stops temporarily at the calculation cycle “b” (a<b<n) and theyaw rate Y(b) for the calculation cycle “b” becomes zero first, thefirst embodiment apparatus sets the yaw rate Ys(b) to zero as shown byan expression (3) described below. As can be understood from thecondition LS4 or RS4, the yaw rate Y(a) for the calculation cycle “a” isnot zero.Ys(b)=0  (3)

(In the expression (3), the yaw rate Y(i) (i=“a” to “b−1”) is not zeroand the yaw rate Y(b) is zero.)

Thereafter, the first embodiment apparatus sets the smoothed yaw rate Ysfor each of the calculation cycle “b+1” to “d” (b<d<n) to zero as shownby an expression (4) described below while the own vehicle V continuesto stop from the calculation cycle “b+1” to “d”, that is, while the yawrate Y continues to be zero.Ys(j)=0  (4)

(In the expression (4), the yaw rate Y(j)=(j=“b+1” to “d”) is zero.)

When the own vehicle V starts to turn after the own vehicle V stopstemporarily, the yaw rate Y changes from the zero value to the non-zerovalue. In this case, the smoothed yaw rate Ys calculated by any of theexpressions (1L) to (2R) may be calculated as a generally zero valueeven though the actual yaw rate Y is the non-zero value. In this case,the inaccurate value is calculated.

Accordingly, when the yaw rate Y changes from the zero value to thenon-zero value after the left turn start condition is satisfied, thefirst embodiment apparatus calculates the smoothed yaw rate Ys of theown vehicle V turning left as described below.

When a first situation described below occurs and the number of theconsecutive yaw rates Y(d+1) to Y(n) becomes larger than or equal to thenumber “M”, the first embodiment apparatus calculates the average of theconsecutive yaw rates Y(n−(M−1)) to Y(n) as the smoothed yaw rate Ys(n)as shown by an expression (5L) described below. The first situation is asituation that the left turn waiting condition is satisfied, the ownvehicle V continues to stop until the calculation cycle “d”, the ownvehicle V starts to turn left at the calculation cycle “d+1” and the ownvehicle V continues to turn left without stopping until the calculationcycle “n”, that is, the yaw rate Y continues not to be zero from thecalculation cycle “d+1” to the calculation cycle “n”.Ys(n)={Y(n−(M−1))+ . . . +Y(n−1)+Y(n)}/M  (5L)

(In the expression (5L), the yaw rate Y(k) (k=“d+1” to “n”) is thenon-zero value and the number “n−d” is larger than or equal to thenumber “M”.)

On the other hand, when the first situation occurs and the number of theconsecutive yaw rates Y(d+1) to Y(n) is smaller than the number “M”, thefirst embodiment apparatus calculates the average of the yaw ratesY(d+1) to Y(n) as the smoothed yaw rate Ys(n) as shown by an expression(6L) described below.Ys(n)={Y(d+1)+ . . . +Y(n−1)+Y(n)}/(n−d)  (6L)

(In the expression (6L), the yaw rate Y(k) (k=“d+1” to “n”) is thenon-zero value and the number “n−d” is smaller than the number “M”.)

Accordingly, when the yaw rate Y changes from the zero value to thenon-zero value after the right turn start condition is satisfied, thefirst embodiment apparatus calculates the smoothed yaw rate Ys of theown vehicle V turning right as described below.

When a second situation described below occurs and the number of theconsecutive yaw rates Y(d+1) to Y(n) becomes larger than or equal to thenumber “M”, the first embodiment apparatus calculates the average of theconsecutive yaw rates Y(n−(M−1)) to Y(n) multiplied by “−1”,respectively as the smoothed yaw rate Ys(n) as shown by an expression(5R) described below. The second situation is a situation that the rightturn waiting condition is satisfied, the own vehicle V continues to stopuntil the calculation cycle “d”, the own vehicle V starts to turn rightat the calculation cycle “d+1” and the own vehicle V continues to turnright without stopping until the calculation cycle “n”, that is, the yawrate Y continues not to be zero from the calculation cycle “d+1” to thecalculation cycle “n”.Ys(n)={(−Y(n−(M−1)))+ . . . +(−Y(n−1))+(−Y(n))}/M  (5R)

(In the expression (5R), the yaw rate Y(k) (k=“d+1” to “n”) is thenon-zero value and the number “n−d” is larger than or equal to thenumber “M”.)

On the other hand, when the second situation occurs and the number ofthe consecutive yaw rates Y(d+1) to Y(n) is smaller than the number “M”,the first embodiment apparatus calculates the average of the yaw ratesY(d+1) to Y(n) multiplied by “−1”, respectively as the smoothed yaw rateYs(n) as shown by an expression (6R) described below.Ys(n)={(−Y(d+1))+ . . . +(−Y(n−1))+(−Y(n))}/(n−d)  (6R)

(In the expression (6R), the yaw rate Y(k) (k=“d+1” to “n”) is thenon-zero value and the number “n−d” is smaller than the number “M”.)

<Calculation of Turning Angle>

The first embodiment apparatus uses the total turn angle θtotal(n)corresponding to the angle of the turning of the own vehicle V from thecalculation cycle “0” to the calculation cycle “n” for calculatingeffective lengths of predicted routes as described later. The firstembodiment apparatus calculates an instantaneous turning angle θcorresponding to an angle of the turning of the own vehicle V for thepredetermined calculation time Tcal for calculating the total turn angleθtotal(n).

The first embodiment apparatus sets the instantaneous turn angle θ(0) tozero as shown by an expression (7) described below when the left orright turn waiting condition is satisfied, that is, when the calculationcycle “n” is the calculation cycle “0”.θ(0)=0°  (7)

After the calculation cycle “n” is the calculation cycle “0”, that is,while the calculation cycle “n” is larger than or equal to thecalculation cycle “1”, the first embodiment apparatus calculates theinstantaneous turn angle θ(n) by multiplying the smoothed yaw rate Ys(n)by the predetermined calculation time Tcal as shown by an expression (8)described below until the first embodiment apparatus makes the left orright turn end determination.θ(n)=Ys(n)·Tcal  (8)

When the left or right turn waiting condition is satisfied, that is, thecalculation cycle “n” is set to the calculation cycle “0”, the firstembodiment apparatus sets the total turn angle θtotal(0) to “0°”, thatis, initializes the total turn angle θtotal(0) as shown by an expression(9) described below.θtotal(0)=0°  (9)

After the calculation cycle “n” is set to the cycle “0”, that is, whilethe calculation cycle “n” is larger than or equal to the calculationcycle “1”, the first embodiment apparatus calculates the total turnangle θtotal(n) by adding the instantaneous turn angle θ(n) to thelastly-calculated turn angle θtotal(n−1) as shown by an expression (10)described below. Thereby, the first embodiment apparatus canappropriately calculate the total turn angle of the own vehicle V whenthe own vehicle V turns left or right in the intersection.θtotal(n)=θtotal(n−1)+θ(n)  (10)

<Calculation of Turn Radius>

The first embodiment apparatus acquires two predicted vehicle movingroutes as described below. Each of the predicted vehicle moving routesis expressed by a circle. A radius of one of the predicted vehiclemoving routes is different from a radius of the other predicted vehiclemoving route. Each of the radii of the circles expressing the predictedvehicle moving routes, respectively is calculated on the basis of aradius R of a circle which the vehicle base point O (see FIG. 2) ispredicted to pass. Hereinafter, the radius R will be referred to as “theturn radius R”. The first embodiment apparatus calculates the turnradius R each time the predetermined calculation time Tcal elapses asdescribed below while the own vehicle V is turning left or right.

When the smoothed yaw rate Ys(n) is larger than a predeterminedthreshold Y0, the first embodiment apparatus calculates the turn radiusR(n) by dividing the vehicle speed SPD(n) by the smoothed yaw rate Ys(n)as shown by an expression (11) described below, independently of whetherthe own vehicle V is in any of the left turn waiting state L1, the rightturn waiting state R1, the left turn state L2 and the right turn stateR2. In other words, when the smoothed yaw rate Ys(n) is larger than thepredetermined threshold Y0, the turn radius R(n) corresponds to acurvature radius at the vehicle base point O(n) (see FIG. 4). In thisembodiment, the predetermined threshold Y0 is 10⁻⁶ and hereinafter, willbe referred to as “the straight moving threshold Y0”.R(n)=SPD(n)/Ys(n)  (11)

The straight moving threshold Y0 is a threshold for avoiding the turnradius R(n) calculated by dividing the vehicle speed SPD(n) by thesmoothed yaw rate Ys(n) close to zero, from being excessively large.

The smoothed yaw rate Ys(n) is larger than the straight moving thresholdY0 when the own vehicle V is turning in the same direction as thedirection of the left or right turning of the own vehicle V. On theother hand, the smoothed yaw rate Ys(n) is smaller than or equal to thestraight moving threshold Y0 when the negative smoothed yaw rate Ys iscalculated, for example, since the own vehicle V stops temporarily orthe own vehicle V moves straight or the own vehicle V turns at leasttemporarily in a direction different from the direction of the left orright turning of the own vehicle V.

When the smoothed yaw rate Ys(n) is smaller than or equal to thestraight moving threshold Y0 and the own vehicle V is in the left orright turn waiting state L1 or R1, the first embodiment apparatuscalculates the turn radius R(n) by using a first method as describedlater. When the smoothed yaw rate Ys(n) is smaller than or equal to thestraight moving threshold Y0 and the own vehicle V is in the left orright turn state L2 or R2, the first embodiment apparatus calculates theturn radius R(n) by using a second method different from the firstmethod as described later.

In particular, when the own vehicle V is in the left or right turnwaiting state L1 or R1, the own vehicle V does not turn left or rightand is set to turn left or right. In this case, the own vehicle V islikely to be near an entrance of the intersection. The inventors of thisapplication have realized that usage of a generally straight line as thepredicted vehicle moving route in the intersection can cause the firstembodiment apparatus to appropriately draw the driver's attention whenthe smoothed yaw rate Ys(n) is smaller than or equal to the straightmoving threshold Y0.

According to the first method, when the own vehicle V is in the left orright turn waiting state L1 or R1 and the smoothed yaw rate Ys(n) issmaller than or equal to the straight moving threshold Y0, the firstembodiment apparatus sets the turn radius R(n) to a predetermined valuecorresponding to a value considerably larger than the turn radius of theown vehicle V turning left or right in the typical intersection as shownby an expression (12) described below. Thereby, as described later, thepredicted vehicle moving route for the intersection is set to thegenerally straight line. In the first embodiment, the predeterminedvalue is 12700 m and hereinafter, will be referred to as “the straightequivalent value Rc”.R(n)=Rc=12700 m  (12)

On the other hand, according to the second method, when the own vehicleV is in the left or right turn state L2 or R2, the own vehicle V hasstarted to turn left or right. When the own vehicle V has started toturn left or right and the smoothed yaw rate Ys(n) is smaller than orequal to the straight moving threshold Y0, the own vehicle V is likelyto stop temporarily or the own vehicle V is likely to turn temporarilyin the direction opposite to the turning direction of the own vehicle Vturning left or right.

Accordingly, when the own vehicle V is in the left or right turn stateL2 or R2 and the smoothed yaw rate Ys(n) is smaller than or equal to thestraight moving threshold Y0, the first embodiment apparatus sets theturn radius R(n) to the turn radius R(c) acquired at the lastcalculation cycle “c” of the past calculation cycles, at which theacquired smoothed yaw rate Ys is larger than the straight movingthreshold Y0, as shown by an expression (13) described below. The pastcalculation cycles are the calculation cycles before the present time.R(n)=R(c)  (13)

It should be noted that the turn radius R(n) is not limited to 12700 mwhen the own vehicle V is in the left or right turn waiting state L1 andR1 and the smoothed yaw rate Ys(n) is smaller than or equal to thestraight moving threshold Y0. When the own vehicle V is in the left orright turn waiting state L1 or R1 and the smoothed yaw rate Ys(n) issmaller than or equal to the straight moving threshold Y0, the turnradius R(n) may be set to an optional value considerably larger than theturn radius of the own vehicle V in the typical intersection.

<Calculation of Turning Center>

The first embodiment apparatus calculates coordinates (Cx(n), Cy(n)) ofa center of the turning of the own vehicle V at the calculation cycle“n” in the left turn waiting state L1 or the left turn state L2 andcoordinates (Cx(n), Cy(n)) of a center of the turning of the own vehicleV at the calculation cycle “n” in the right turn waiting state R1 or theright turn state R2 on the basis of the turn radius R(n) as describedbelow. Hereinafter, the coordinates (Cx(n), Cy(n)) will be referred toas “the turn center coordinates (Cx(n), Cy(n))”.

When the own vehicle V is in the left turn waiting state L1 or the leftturn state L2, the first embodiment apparatus calculates, as the turncenter coordinates (Cx(n), Cy(n)), a position which is located on a lineextending in a direction perpendicular to the moving direction of theown vehicle V at the calculation cycle “n” and passing through thevehicle base point O(n), is away from the vehicle base point O(n) by theturn radius R(n) and is located at the left side of a line extending inthe moving direction of the own vehicle V at the calculation cycle “n”and passing through the vehicle base point O(n). The moving direction ofthe own vehicle V at the calculation cycle “n” can be calculated, usingthe smoothed yaw rate Ys(n) and hereinafter, will be referred to as “thevehicle moving direction TD”.

When the own vehicle V is in the right turn waiting state R1 or theright turn state R2, the first embodiment apparatus calculates, as theturn center coordinates (Cx(n), Cy(n)), a position which is located onthe line extending in the direction perpendicular to the vehicle movingdirection TD at the calculation cycle “n” and passing through thevehicle base point O(n), is away from the vehicle base point O(n) by theturn radius R(n) and is located at the right side of the line extendingin the vehicle moving direction TD at the calculation cycle “n” andpassing through the vehicle base point O(n) (see FIG. 4).

In an example shown in FIG. 4, the own vehicle V is turning right at theconstant vehicle speed SPD and the constant smoothed yaw rate Ys. Thus,while the own vehicle V is turning right, the turn radius R(n) isconstant and the turn center coordinates (Cx(n), Cy(n)) are constant.However, when the vehicle speed SPD and the smoothed yaw rate Ys changewhile the own vehicle V is turning right, the turn radius R(n) changes,depending on the calculation cycle and as a result, the turn centercoordinates (Cx(n), Cy(n)) are not constant. Also, in this case, thefirst embodiment apparatus can appropriately calculate the effectivelength LLe of a predicted left end route described later and theeffective length LRe of a predicted right end route by calculating thetotal turn angle θtotal(n) as described above.

<Calculation of Left and Right End Turn Radii>

The first embodiment apparatus calculates a left end turn radius RL(n)and a right end turn radius RR(n) on the basis of the turn radius R(n)as described below.

When the own vehicle V turns left, that is, when the own vehicle V is inthe left turn waiting state L1 or the left turn state L2, the firstembodiment apparatus calculates the left end turn radius RL(n) bysubtracting a half W/2 of a width W of the own vehicle V from the turnradius R(n) as shown by an expression (15) described below andcalculates the right end turn radius RR(n) by adding the half W/2 to theturn radius R(n) as shown by an expression (16) described below.RL(n)=R(n)−W/2  (15)RR(n)=R(n)+W/2  (16)

When the own vehicle V turns right, that is, when the own vehicle V isin the right turn waiting state R1 or the right turn state R2, the firstembodiment apparatus calculates the left end turn radius RL(n) by addingthe half W/2 to the turn radius R(n) as shown by an expression (17)described below and calculates the right end turn radius RR(n) bysubtracting the half W/2 from the turn radius R(n) as shown by anexpression (18) described below.RL(n)=R(n)+W/2  (17)RR(n)=R(n)−W/2  (18)

As shown in FIG. 2, a left end OL(n) of the front end portion of the ownvehicle V at the calculation cycle “n” corresponds to a position whichis located on the line extending in the direction perpendicular to thevehicle moving direction TD and passing through the vehicle base pointO(n), is away from the vehicle base point O(n) by the half W/2 and islocated at the left side of the line extending in the vehicle movingdirection TD and passing through the vehicle base point O(n). A rightend OR(n) of the front end portion of the own vehicle V at thecalculation cycle “n” corresponds to a position which is located on theline extending in the direction perpendicular to the vehicle movingdirection TD and passing through the vehicle base point O(n), is awayfrom the vehicle base point O(n) by the half W/2 and is located at theright side of the line extending in the vehicle moving direction TD andpassing through the vehicle base point O(n). Hereinafter, the left endOL(n) of the front end portion of the own vehicle V at the calculationcycle “n” will be referred to as “the vehicle left end OL(n)” and theright end OR(n) of the front end portion of the own vehicle V at thecalculation cycle “n” will be referred to as “the vehicle right endOL(n)”.

Thus, the left end turn radius RL(n) corresponds to a radius of a circleexpressing a route that the vehicle left end OL(n) is predicted to passand the right end turn radius RR(n) corresponds to a radius of a circleexpressing a route that the vehicle right end OR(n) is predicted topass.

The width W of the own vehicle V is previously set for each vehicle, towhich the first embodiment apparatus is to be applied. The width W maybe larger than the actual width of the vehicle and may be smaller thanthe actual width of the vehicle.

<Estimation of Predicted Left and Right End Routes>

When the own vehicle V is turning left or right, the first embodimentapparatus estimates a route which the vehicle left end OL is predictedto pass and a route which the vehicle right end OR is predicted to passeach time the predetermined calculation time Tcal elapses as describedbelow. Hereinafter, the route which the vehicle left end OL is predictedto pass, will be referred to as “the predicted left end route” and theroute which the vehicle right end OR is predicted to pass, will bereferred to as “the predicted right end route”.

First, the first embodiment apparatus calculates a predicted left endroute expression fL(n) expressing the predicted left end route at thecalculation cycle “n” and a predicted right end route expression fR(n)expressing the predicted right end route at the calculation cycle “n”(see FIG. 4).

In particular, the first embodiment apparatus calculates, as thepredicted left end route expression fL(n), an expression of a circlehaving a center defined by the turn center coordinates (Cx(n), Cy(n))and the left end turn radius RL(n) as shown by an expression (19)described below. Further, the first embodiment apparatus calculates, asthe predicted right end route expression fR(n), an expression of acircle having a center defined by the turn center coordinates (Cx(n),Cy(n)) and the right end turn radius RR(n) as shown by an expression(20) described below.(x−Cx(n))²+(y−Cy(n))² =RL(n)²  (19)(x−Cx(n))²+(y−Cy(n))² =RR(n)²  (19)

As described above, when the own vehicle V is in the left or right turnwaiting state L1 or R1 and the smoothed yaw rate Ys(n) is smaller thanor equal to the straight moving threshold Y0 (=10⁻⁶), the turn radiusR(n) is set to the straight equivalent value Rc (=12700 m) (see theexpression (12)). In this case, each of the predicted left and right endroute expressions fL(n) and fR(n) is approximated by an expression of astraight line extending in the vehicle moving direction TD at thecalculation cycle “n”, respectively as shown in FIG. 3.

<Calculation of Effective Lengths of Predicted Left and Right EndRoutes>

When the own vehicle V is turning left or right, the first embodimentapparatus calculates the effective length LLe of the predicted left endroute and the effective length LRe of the predicted right end route eachtime the predetermined calculation time Tcal elapses as described later.When there is an object which crosses at least one of portions of thepredicted left and right end routes corresponding to the effectivelengths LLe and LRe, respectively within a predetermined time, the firstembodiment apparatus performs the attention operation to the driver.Hereinafter, the effective length LLe of the predicted left end routewill be referred to as “the effective left end length LLe” and theeffective length LRe of the predicted right end route will be referredto as “the effective right end length LRe”.

As described above, when the own vehicle V is in the left or right turnwaiting state L1 or R1 and the smoothed yaw rate Ys(n) is smaller thanor equal to the straight moving threshold Y0, each of the predicted leftand right end route expressions fL(n) and fR(n) is approximated by theexpression of the straight line extending in the vehicle movingdirection TD at the calculation cycle “n”, respectively. In this case,the first embodiment apparatus sets the effective left and right endlengths LLe(n) and LRe(n), using a length of a width of a road, intowhich the own vehicle V is to enter after the own vehicle V completesthe left or right turning in the typical intersection as bases,respectively as shown by an expression (21) described below (see a thickline in FIG. 3). For example, the length of the road, into which the ownvehicle V is to enter after the own vehicle V completes the left orright turning in the typical intersection, may be set to an optionalvalue between 15 m to 20 m and in the first embodiment, is set to 15 m.LLe(n)=LRe(n)=15 m  (21)

When the own vehicle V is in the left or right turn waiting state L1 orR1 and the smoothed yaw rate Ys(n) is larger than the straight movingthreshold Y0 or when the own vehicle V is in the left or right turnstate L2 or R2, the first embodiment apparatus calculates, as theeffective left and right end lengths LLe and LRe, lengths of thepredicted left and right end routes, which the own vehicle V ispredicted to turn or move or travel while the total turn angle θtotal ofthe own vehicle V changes from the present total turn angle θtotal tothe turn end angle θend, respectively.

In particular, the first embodiment apparatus calculates the effectiveleft and right end lengths LLe(n) and LRe(n) by expressions (22) and(23) described below, respectively. The first embodiment apparatuscalculates an angle θre which the own vehicle V turns until the totalturn angle θtotal reaches the turn end angle θend (=90°) by subtractingthe total turn angle θtotal from the turn end angle θend. The firstembodiment apparatus converts the unit of the angle θre to the radian.Further, the first embodiment apparatus calculates the effective leftend length LLe(n) by multiplying the angle θre having the converted unitby the left end turn radius RL(n) (see the thick line in FIG. 4) andcalculates the effective right end length LRe(n) by multiplying theangle θre having the converted unit by the right end turn radius RR(n)(see the thick line in FIG. 4). Hereinafter, the angle θre which the ownvehicle V turns until the total turn angle θtotal reaches the turn endangle θend, will be referred to as “the remaining turn angle θre”.LLe(n)=RL(n)·(90°−θtotal(n))·π/180°  (22)LRe(n)=RR(n)·(90°−θtotal(n))·π/180°  (23)

<Attention Operation to Driver>

When the own vehicle V is turning left or right, the first embodimentapparatus determines whether there is an object which crosses at leastone of the portions of the predicted left and right end routescorresponding to the effective left and right end lengths LLe and LRe,respectively within the predetermined time each time the predeterminedcalculation time Tcal elapses. Hereinafter, the portion of the predictedleft end route corresponding to the effective left end length LLe willbe referred to as “the effective portion LLep of the predicted left endroute” or “the effective portion of the predicted route”. Further, theportion of the predicted right end route corresponding to the effectiveright end length LRe will be referred to as “the effective portion LRepof the predicted right end route” or “the effective portion of thepredicted route”. Furthermore, the object which crosses at least one ofthe effective portions LLep and LRep of the predicted left and right endroutes within the predetermined time, is a moving object andhereinafter, will be referred to as “the target object”.

When the first embodiment apparatus determines that there is the targetobject, the first embodiment apparatus determines that the object maycross the effective portion of the predicted route. In this case, thefirst embodiment apparatus performs the attention operation for drawingthe driver's attention. The first embodiment apparatus performsprocesses described below for determining whether there is the targetobject.

<Acquisition of Object Information>

When the own vehicle V is turning left or right, the first embodimentapparatus acquires information on the object existing around the ownvehicle V such as a position of the object with respect to the ownvehicle V, a moving direction of the object and a moving speed of theobject as object information each time the predetermined calculationtime Tcal elapses. In an example shown in FIG. 5, the first embodimentapparatus acquires the object information on the objects A to D existingaround the own vehicle V at the calculation cycle “n”.

<Calculation of Predicted Route of Object>

The first embodiment apparatus calculates a predicted route expression gof a half line extending from the position of the object in the movingdirection of the object on the basis of the object information. In theexample shown in FIG. 5, the first embodiment apparatus calculatespredicted route expressions ga(n), gb(n), gc(n) and gd(n) extending fromthe positions of the objects A to D in the moving directions of theobjects A to D (see arrows in FIG. 5) on the basis of the objectinformation on the objects A to D acquired at the calculation cycle “n”,respectively. Hereinafter, the predicted route expression g(n) will besimply referred to as “the expression g(n)”. In this case, theexpression g(n) is any of the expressions ga(n), gb(n), gc(n) and gd(n).

<First Crossing Condition>

The first embodiment apparatus determines whether a first crossingcondition that the straight line expressed by the expression g(n)crosses at least one of the effective portions LLep and LRep of thepredicted left and right end routes, is satisfied. It should be notedthat in this description, when the predicted moving route of the objectis tangent to the effective portion LLep or LRep of the predicted leftor right end route, the predicted moving route of the object does notcross the effective portion LLep or LRep of the predicted left or rightend route. Hereinafter, the straight line expressed by the expressiong(n) will be referred to as “the straight line g(n)”.

In the example shown in FIG. 5, the straight line expressed by theexpression ga(n) crosses the effective portion LLep(n) of the predictedleft end route shown by the thick solid line at a point A1 and theeffective portion LRep(n) of the predicted right end route shown by thethick solid line at a point A2. Thus, the expression ga(n) satisfies thefirst crossing condition. The straight line expressed by the expressiongb(n) crosses the effective portion LLep(n) of the predicted left endroute at a point B1. Thus, the expression gb(n) satisfies the firstcrossing condition.

On the other hand, the straight lines expressed by the expressions gc(n)and gd(n), respectively do not cross the effective portions LLep(n) andLRep(n) of the predicted left and right end routes. Thus, theexpressions gc(n) and gd(n) do not satisfy the first crossing condition.

<Calculation of Coordinates of Crossing Point P>

When the expression g(n) satisfies the first crossing condition, thefirst embodiment apparatus calculates the number of points which thestraight line g(n) crosses the effective portion LLep(n) of thepredicted left end route and/or the effective portion LRep(n) of thepredicted right end route. Hereinafter, the point which the straightline g(n) crosses any of the effective portions LLep(n) and LRep(n) ofthe predicted left and right end routes, will be referred to as “thefirst crossing point”.

When the number of the first crossing points is two, the firstembodiment apparatus calculates coordinates of a point which thestraight line g(n) first crosses the effective portion of the predictedroute in the moving direction of the object, as coordinates of acrossing point P(n). On the other hand, when the number of the firstcrossing point is one, the first embodiment apparatus calculatescoordinates of the first crossing point as the coordinates of thecrossing point P(n).

In the example shown in FIG. 5, regarding the expression ga(n), thefirst crossing points are points A1 and A2 and thus, the number of thefirst crossing points is two. Thus, the first embodiment apparatuscalculates the coordinates of the point A1 which the straight lineexpressed by the expression ga(n) crosses the effective portion LLep(n)of the predicted left end route in the moving direction of the object A(i.e., a downward direction in a paper of FIG. 5), as the coordinates ofthe crossing point Pa(n). On the other hand, regarding the expressiongb(n), the first crossing point is a point B1 and thus, the number ofthe first crossing point is one. Thus, the first embodiment apparatuscalculates the coordinates of the point B1 as the coordinates of thecrossing point Pb(n).

<Calculation of Time t1>

The first embodiment apparatus calculates a time t1 predictivelyrequired for the object to reach the predicted route for determiningwhether a time condition described later is satisfied. In particular,the first embodiment apparatus calculates the time predictively requiredfor the object corresponding to the straight line g(n) which crosses theeffective portion of the predicted route at the point P(n), to reach thepoint P(n), as a first time t1(n). The first time t1(n) is calculated bydividing a length of the straight line from the position of the objectat the calculation cycle “n” to the point P(n) by the moving speedSPDs(n) of the object.

In the example shown in FIG. 5, the first embodiment apparatuscalculates the first time t1a(n) predictively required for the object Ato reach the point Pa(n) and the first time t1b(n) predictively requiredfor the object B to reach the point Pb(n).

<Time Condition>

The first embodiment apparatus determines whether a time condition thatthe first time t1(n) is smaller than or equal to a first predeterminetime t1th (in this embodiment, four seconds), is satisfied. When thetime condition is satisfied for any of the expressions g(n), the firstembodiment apparatus determines that there is/are the target object(s).On the other hand, when the time condition is not satisfied for theexpressions g(n), the first embodiment apparatus determines that thereis no target object.

In the example shown in FIG. 5, when the first time t1a(n) is threeseconds and the first time t1b(n) is ten seconds, the first time t1a(n)is smaller than or equal to the first predetermined time t1th and thus,the time condition is satisfied for the expression ga(n). In this case,the first embodiment apparatus determines that there is the targetobject (i.e. the object A).

On the other hand, when the first time t1a(n) is five seconds and thefirst time b(n) is ten seconds, the first times t1a(n) and t1b(n) arelarger than the first predetermine time t1th and thus, the timecondition is not satisfied for the expressions ga(n) and gb(n). In thiscase, the first embodiment apparatus determines that there is no targetobject.

When the first embodiment apparatus determines that there is/are thetarget object(s), the first embodiment apparatus performs the attentionoperation for drawing the attention of the driver of the own vehicle V.On the other hand, when the first embodiment apparatus determines thatthere is no target object, the first embodiment apparatus does notperform the attention operation.

<Concrete Operation of First Embodiment Apparatus>

Below, a concrete operation of the first embodiment apparatus will bedescribed. The CPU of the driving assist ECU 10 of the first embodimentapparatus is configured or programmed to execute a routine shown by aflowchart in FIG. 6 each time the predetermined calculation time Tcalelapses.

At a predetermined timing, the CPU starts a process from a step 600 ofFIG. 6 and then, proceeds with the process to a step 605 to acquire theown vehicle information and store the thus-acquired own vehicleinformation in the RAM of the driving assist ECU 10. Thereafter, the CPUproceeds with the process to a step 610 to determine whether the leftturn waiting condition is satisfied on the basis of the own vehicleinformation.

When the left turn waiting condition is satisfied, the CPU determines“Yes” at the step 610 and then, sequentially executes processes of steps615 and 620 described below. Thereafter, the CPU proceeds with theprocess to a step 625. As described above, the left turn waitingcondition is satisfied only once for one intersection. Therefore, theCPU determines “Yes” at the step 610 only once for one intersection.

Step 615: The CPU sets a value of a left turn waiting flag XLW to “1”.The value of the left turn waiting flag XLW has been set to “1” untilthe left turn start condition is satisfied after the left turn waitingcondition is satisfied. Further, the value of the left turn waiting flagXLW is set to “0” when the left turn start condition is satisfied (see astep 640 described later).

Step 620: The CPU sets the total turn angle θtotal to 0°, that is,initializes the total turn angle θtotal. A process of the step 620 isexecuted when the CPU determines “Yes” at the step 610. Therefore, aninitializing process of the total turn angle θtotal is executed onlyonce when the left turn waiting condition is satisfied and theinitializing process is not executed until the own vehicle V completesthe left turning.

When the CPU proceeds with the process to the step 625, the CPU executesa routine shown by a flowchart in FIG. 7. Therefore, when the CPUproceeds with the process to the step 625, the CPU starts a process froma step 700 of FIG. 7 and then, sequentially executes processes of steps705 to 715 described below. Thereafter, the CPU proceeds with theprocess to a step 720.

Step 705: The CPU calculates the smoothed yaw rate Ys(n) in accordancewith any of the expressions (1L), (2L), (3), (4), (5L) and (6L) andstores the thus-calculated smoothed yaw rate Ys(n) in the RAM.

Step 710: The CPU calculates the instantaneous turn angle θ(n) inaccordance with any of the expressions (7) and (8) and stores thethus-calculated instantaneous turn angle θ(n) in the RAM.

Step 715: The CPU calculates the total turn angle θtotal(n) inaccordance with any of the expressions (9) and (10) and stores thethus-calculated total turn angle θtotal(n) in the RAM.

When the CPU proceeds with the process to the step 720, the CPUdetermines whether the total turn angle θtotal(n) is smaller than orequal to the turn end angle θend (=90°), that is, whether the ownvehicle V turns left. When the total turn angle θtotal(n) is smallerthan or equal to the turn end angle Bend, the CPU determines “Yes” atthe step 720 and then, proceeds with the process to a step 725 todetermine whether the smoothed yaw rate Ys(n) is larger than thestraight moving threshold Y0 (=10⁻⁶).

When the smoothed yaw rate Ys(n) is larger than the straight movingthreshold Y0, the CPU determines “Yes” at the step 725 and then,executes a process of a step 730 described below. Thereafter, the CPUproceeds with the process to a step 735. It should be noted that it isdetermined “Yes” at the step 725 typically when the own vehicle V turnsleft temporarily while the own vehicle V moves straight to a point wherethe own vehicle V can turn left.

Step 730: The CPU sets the turn radius R(n) to a value obtained bydividing the vehicle speed SPD(n) by the smoothed yaw rate Ys(n) asshown the expression (11) and stores the thus-set turn radius R(n) inthe RAM.

When the smoothed yaw rate Ys(n) is smaller than or equal to thestraight moving threshold Y0 at a time of the CPU executing a process ofthe step 725, the CPU determines “No” at the step 725 and then, executesa process of a step 740 described below. Thereafter, the CPU proceedswith the process to the step 735. It should be noted that it isdetermined “No” at the step 725 typically when the own vehicle V stopsat a red light in an attempt to turn left or when the own vehicle Vmoves straight to the point where the own vehicle V can turn left afterthe left turn waiting condition is satisfied or when the negativesmoothed yaw rate Ys is calculated due to a temporary right turning ofthe own vehicle V while the own vehicle V moves straight to the pointwhere the own vehicle V can turn left after the left turn waitingcondition is satisfied.

Step 740: The CPU sets the turn radius R(n) to the straight lineequivalent value Rc (=12700 m) as shown by the expression (12) andstores the thus-set turn radius R(n) in the RAM.

When the CPU proceeds with the process to the step 735, the CPU sets avalue of a left turn flag XL to “1” and then, proceeds with the processto a step 695 of FIG. 6 via a step 795 to terminate this routine once.

When the total turn angle θtotal(n) is larger than the turn end anglefiend at a time of the CPU executing a process of the step 720, the CPUdetermines “No” at the step 720, that is, the CPU determines that theown vehicle V completes the left turning and then, proceeds with theprocess to a step 745 to set the value of the left turn flag XL to “0”.Thereafter, the CPU proceeds with the process to the step 695 of FIG. 6via the step 795 to terminate this routine once.

When the left turn waiting condition is not satisfied at a time of theCPU executing a process of the step 610 of FIG. 6, the CPU determines“No” at the step 610 and then, proceeds with the process to a step 630to determine whether the left direction blinkers are blinking.

It should be noted that it is determined “No” at the step 610 when thedetermination process of the step 610 is executed after it is determinedthat the left turn waiting condition is first satisfied after it isdetermined last time that the left or right turning of the own vehicle Vis completed or when the left turn waiting condition has not beensatisfied after it is determined last time that the left or rightturning of the own vehicle V is completed.

When the CPU executes the determination process of the step 610 afterthe CPU determines that the left turn waiting condition is firstsatisfied after the CPU determines last time that the left or rightturning of the own vehicle V is completed, the CPU determines “No” atthe step 610. When the CPU determines “No” at the step 610 as describedabove and the driver continues to cause the left direction blinkers toblink in an attempt to turn the own vehicle V left, the CPU determines“Yes” at the step 630 and then, proceeds with the process to a step 635.

When the CPU proceeds with the process to the step 635, the CPUdetermines whether the value of the left turn waiting flag XLW is “0”and the left turn start condition is satisfied. The CPU determineswhether the left turn start condition is satisfied on the basis of theown vehicle information.

When the value of the left turn waiting flag XLW is “0” or the left turnstart condition is satisfied, the CPU determines “Yes” at the step 635and then, proceeds with the process to a step 640.

When the left turn waiting condition is once satisfied while the CPUdetermines last time that the left or right turning of the own vehicle Vis completed, the value of the left turn waiting flag XLW is set to “1”at the step 615. Therefore, as far as the left turn start condition issatisfied, the CPU determines “Yes” at the step 635, that is, the CPUdetermines that the own vehicle V turns left.

On the other hand, when the value of the left turn waiting flag XLW is“1” or the left turn start condition is not satisfied at a time of theCPU executing a process of the step 635, the CPU determines “No” at thestep 635 and then, proceeds with the process to the step 625 to executethe routine shown in FIG. 7 described above. It should be noted that theCPU determines “No” at the step 635 typically when the own vehicle Vdoes not start to turn left after the left turn waiting condition issatisfied.

When the CPU proceeds with the process to the step 640, the CPU sets thevalue of the left turn waiting flag XLW to “0” and then, proceeds withthe process to a step 645. Thereby, the value of the left turn waitingflag XLW is “0” from when the own vehicle V starts to turn left, thatis, the left turn start condition is satisfied to when the left turnwaiting condition is satisfied at the next intersection. Further, thevalue of the left turn waiting flag XLW is set to “1” when the ownvehicle V is set to turn left at the next intersection, that is, theleft turn waiting condition is satisfied at the next intersection (seethe steps 610 and 615).

Therefore, the value of the left turn waiting flag XLW is “0” until theleft turn waiting condition is satisfied at the next intersection eventhough the left turn start condition becomes unsatisfied after the leftturn start condition is first satisfied (see a determination “Yes” atthe step 635). Thus, the CPU determines “Yes” at the step 635, that is,the CPU determines that the own vehicle V is turning left.

When the CPU proceeds with the process to the step 645, the CPU executesa routine shown by a flowchart in FIG. 8. Therefore, when the CPUproceeds with the process to the step 645, the CPU starts a process froma step 800 of FIG. 8 and then, sequentially executes processes of steps805 to 815 described below. Thereafter, the CPU proceeds with theprocess to a step 820.

Step 805: The CPU calculates the smoothed yaw rate Ys(n) in accordancewith any of the expressions (1L), (2L), (3), (4), (5L) and (6L).

Step 810: The CPU calculates the instantaneous turn angle θ(n) inaccordance with the expression (8).

Step 815: The CPU calculates the total turn angle θtotal(n) inaccordance with the expression (10).

When the CPU proceeds with the process to the step 820, the CPUdetermines whether the total turn angle θtotal(n) is smaller than orequal to the turn end angle θend (=90°). When the total turn angleθtotal(n) is smaller than or equal to the turn end angle θend, the CPUdetermines “Yes” at the step 820 and then, proceeds with the process toa step 825 to determine whether the smoothed yaw rate Ys(n) is largerthan the straight moving threshold Y0.

When the smoothed yaw rate Ys(n) is larger than the straight movingthreshold Y0, the CPU determines “Yes” at the step 825 and then,executes a process of a step 830 described below. Thereafter, the CPUproceeds with the process to a step 835. It should be noted that it isdetermined “Yes” at the step 825 typically when the own vehicle V isturning left after the own vehicle V starts to turn left.

Step 830: The CPU sets the turn radius R(n) to a value obtained bydividing the vehicle speed SPD(n) by the smoothed yaw rate Ys(n) asshown by the expression (11) and stores the thus-set turn radius R(n) inthe RAM.

On the other hand, when the smoothed yaw rate Ys(n) is smaller than orequal to the straight moving threshold Y0, the CPU determines “No” atthe step 825 and then, executes a process of a step 840 described below.Thereafter, the CPU proceeds with the process to the step 835. It shouldbe noted that it is determined “No” at the step 825 typically when theown vehicle V stops temporarily at the center area of the intersectionto wait for the oncoming vehicle, the walking person and the like topass the intersection after the left turn start condition is satisfiedor when the negative smoothed yaw rate Ys is calculated due to atemporary right turning of the own vehicle V after the left turn startcondition is satisfied.

Step 840: The CPU sets the turn radius R(c) acquired at the calculationcycle “c” as the turn radius R(n) as shown by the expression (13) andstores the thus-set turn radius R(n) in the RAM.

When the CPU proceeds with the process to the step 835, the CPU sets thevalue of the left turn flag XL to “1” and then, proceeds with theprocess to the step 695 of FIG. 6 via a step 895 to terminate thisroutine once.

When the total turn angle θtotal(n) is larger than the turn end angleθend at a time of the CPU executing a process of the step 820, the CPUdetermines “No” at the step 820 and then, proceeds with the process to astep 845 to set the value of the left turn flag XL to “0”. Thereafter,the CPU proceeds with the process to the step 695 of FIG. 6 via the step895 to terminate this routine once.

When the left direction blinkers do not blink at a time of the CPUexecuting a process of the step 630 of FIG. 6, the CPU determines “No”at the step 630 and then, executes a process of a step 650 describedbelow. Thereafter, the CPU proceeds with the process to a step 655.

Step 650: The CPU sets the value of the left turn waiting flag XLW to“0”. Thereby, the value of the left turn waiting flag XLW is “0” whilethe CPU executes processes of the step 655 and steps following the step655.

When the CPU proceeds with the process to the step 655, the CPUdetermines whether the right turn waiting condition is satisfied on thebasis of the own vehicle information. When the right turn waitingcondition is satisfied, the CPU determines “Yes” at the step 655 andthen, sequentially executes processes of steps 660 and 665 describedbelow. Thereafter, the CPU proceeds with the process to a step 670. Asdescribed above, the right turn waiting condition is satisfied only oncefor one intersection. Therefore, the CPU determines “Yes” at the step655 only once for one intersection.

Step 660: The CPU sets a value of a right turn waiting flag XRW to “1”.The value of the right turn waiting flag XRW has been set to “1” untilthe right turn start condition is satisfied after the right turn waitingcondition is satisfied. Further, the value of the right turn waitingflag XRW is set to “0” when the right turn start condition is satisfied(see a step 660 described later).

Step 665: The CPU sets the total turn angle θtotal to 0°, that is,initializes the total turn angle θtotal. The initializing process of thetotal turn angle θtotal is executed only once when the right turnwaiting condition is satisfied and the initializing process is notexecuted until the own vehicle V completes the right turning.

When the CPU proceeds with the process to the step 670, the CPU executesa routine shown by a flowchart in FIG. 9. Therefore, when the CPUproceeds with the process to the step 670, the CPU starts a process froma step 900 of FIG. 9 and then, sequentially executes processes of steps905 to 915 described below. Thereafter, the CPU proceeds with theprocess to a step 920.

Step 905: The CPU calculates the smoothed yaw rate Ys(n) in accordancewith any of the expressions (1R), (2R), (3), (4), (5R) and (6R) andstores the thus-calculated smoothed yaw rate Ys(n) in the RAM.

Step 910: The CPU calculates the instantaneous turn angle θ(n) inaccordance with any of the expressions (7) and (8) and stores thethus-calculated instantaneous turn angle θ(n) in the RAM.

Step 915: The CPU calculates the total turn angle θtotal(n) inaccordance with any of the expressions (9) and (10) and stores thethus-calculated turn angle θtotal(n) in the RAM.

When the CPU proceeds with the process to the step 920, the CPUdetermines whether the total turn angle θtotal(n) is smaller than orequal to the turn end angle θend, that is, whether the own vehicle Vturns right. When the total turn angle θtotal(n) is smaller than orequal to the turn end angle θend, the CPU determines “Yes” at the step920 and then, proceeds with the process to a step 925 to determinewhether the smoothed yaw rate Ys(n) is larger than the straight movingthreshold Y0.

When the smoothed yaw rate Ys(n) is larger than the straight movingthreshold Y0, the CPU determines “Yes” at the step 925 and then,executes a process of a step 930 described below. Thereafter, the CPUproceeds with the process to a step 935. It should be noted that it isdetermined “Yes” at the step 925 typically when the own vehicle V turnsright temporarily while the own vehicle V moves straight to a pointwhere the own vehicle V can turn right after the right turn waitingcondition is satisfied.

Step 930: The CPU sets the turn radius R(n) to a value obtained bydividing the vehicle speed SPD(n) by the smoothed yaw rate Ys(n) asshown the expression (11) and stores the thus-set turn radius R(n) inthe RAM.

When the smoothed yaw rate Ys(n) is smaller than or equal to thestraight moving threshold Y0 at a time of the CPU executing a process ofthe step 925, the CPU determines “No” at the step 925 and then, executesa process of a step 940 described below. Thereafter, the CPU proceedswith the process to the step 935. It should be noted that it isdetermined “No” at the step 925 typically when the own vehicle V stopsat the red light in an attempt to turn right or when the own vehicle Vmoves straight to the point where the own vehicle V can turn right afterthe right turn waiting condition is satisfied or when the negativesmoothed yaw rate Ys is calculated due to a temporary left turning ofthe own vehicle V while the own vehicle V moves straight to the pointwhere the own vehicle V can turn left after the right turn waitingcondition is satisfied.

Step 940: The CPU sets the turn radius R(n) to the straight lineequivalent value Rc as shown by the expression (12) and stores thethus-set turn radius R(n) in the RAM.

When the CPU proceeds with the process to the step 935, the CPU sets avalue of a right turn flag XR to “1” and then, proceeds with the processto the step 695 of FIG. 6 via a step 995 to terminate this routine once.

When the total turn angle θtotal(n) is larger than the turn end angleθend at a time of the CPU executing a process of the step 920, the CPUdetermines “No” at the step 920, that is, the CPU determines that theown vehicle V completes the right turning and then, proceeds with theprocess to a step 945 to set the value of the right turn flag XR to “0”.Thereafter, the CPU proceeds with the process to the step 695 of FIG. 6via the step 995 to terminate this routine once.

When the right turn waiting condition is not satisfied at a time of theCPU executing a process of the step 655 of FIG. 6, the CPU determines“No” at the step 655 and then, proceeds with the process to a step 675to determine whether the right direction blinkers are blinking.

It should be noted that it is determined “No” at the step 655 when adetermination process of the step 655 is executed after it is determinedthat the right turn waiting condition is first satisfied after it isdetermined last time that the left or right turning of the own vehicle Vis completed or when the right turn waiting condition has not beensatisfied after it is determined last time that the left or rightturning of the own vehicle V is completed.

When the CPU executes the determination process of the step 655 afterthe CPU determines that the right turn waiting condition is firstsatisfied after the CPU determines last time that the left or rightturning of the own vehicle V is completed, the CPU determines “No” atthe step 655. When the CPU determines “No” at the step 655 as describedabove and the driver continues to cause the right direction blinkers toblink in an attempt to turn the own vehicle V right, the CPU determines“Yes” at the step 675 and then, proceeds with the process to a step 680.

When the CPU proceeds with the process to the step 680, the CPUdetermines whether the value of the right turn waiting flag XRW is “0”and the right turn start condition is satisfied. The CPU determineswhether the right turn start condition is satisfied on the basis of theown vehicle information.

When the value of the right turn waiting flag XRW is “0” or the rightturn start condition is satisfied, the CPU determines “Yes” at the step680 and then, proceeds with the process to a step 685.

When the right turn waiting condition is once satisfied after the CPUdetermines last time that the left or right turning of the own vehicle Vis completed, the value of the right turn waiting flag XRW is set to “1”at the step 660. Therefore, as far as the right turn start condition hasbeen satisfied, the CPU determines “Yes” at the step 680, that is, theCPU determines that the own vehicle V is turning right.

On the other hand, when the value of the right turn waiting flag XRW is“1” or the right turn start condition is not satisfied at a time of theCPU executing a process of the step 680, the CPU determines “No” at thestep 680 and then, proceeds with the process to the step 670 to executethe routine shown in FIG. 9 described above. It should be noted that theCPU determines “No” at the step 680 typically when the own vehicle Vdoes not start to turn right after the right turn waiting condition issatisfied.

When the CPU proceeds with the process to the step 685, the CPU sets thevalue of the right turn waiting flag XRW to “0” and then, proceeds withthe process to a step 690. Thereby, the value of the right turn waitingflag XRW is “0” from when the own vehicle V starts to turn right, thatis, the right turn start condition is satisfied to when the right turnwaiting condition is satisfied at the next intersection. Further, thevalue of the right turn waiting flag XRW is set to “1” when the ownvehicle V is set to turn right at the next intersection, that is, theright turn waiting condition is satisfied at the next intersection (seethe processes of the steps 655 and 660).

Therefore, the value of the right turn waiting flag XRW is “0” until theright turn waiting condition is satisfied at the next intersection eventhough the right turn start condition becomes unsatisfied after theright turn start condition is first satisfied (see a determination “Yes”at the step 680). Thus, the CPU determines “Yes” at the step 680, thatis, the CPU determines that the own vehicle V turns right.

When the CPU proceeds with the process to the step 690, the CPU executesa routine shown by a flowchart in FIG. 10. Therefore, when the CPUproceeds with the process to the step 690, the CPU starts a process froma step 1000 of FIG. 10 and then, sequentially executes processes ofsteps 1005 to 1015 described below. Thereafter, the CPU proceeds withthe process to a step 1020.

Step 1005: The CPU calculates the smoothed yaw rate Ys(n) in accordancewith any of the expressions (1R), (2R), (3), (4), (5R) and (6R).

Step 1010: The CPU calculates the instantaneous turn angle θ(n) inaccordance with the expression (8).

Step 1015: The CPU calculates the total turn angle θtotal(n) inaccordance with the expression (10).

When the CPU proceeds with the process to the step 1020, the CPUdetermines whether the total turn angle θtotal(n) is smaller than orequal to the turn end angle θend (=90°). When the total turn angleθtotal(n) is smaller than or equal to the turn end angle θend, the CPUdetermines “Yes” at the step 1020 and then, proceeds with the process toa step 1025 to determine whether the smoothed yaw rate Ys(n) is largerthan the straight moving threshold Y0.

When the smoothed yaw rate Ys(n) is larger than the straight movingthreshold Y0, the CPU determines “Yes” at the step 1025 and then,executes a process of a step 1030 described below. Thereafter, the CPUproceeds with the process to a step 1035. It should be noted that it isdetermined “Yes” at the step 1025 typically when the own vehicle V turnsright after the own vehicle V starts to turn right.

Step 1030: The CPU sets the turn radius R(n) to a value obtained bydividing the vehicle speed SPD(n) by the smoothed yaw rate Ys(n) asshown by the expression (11) and stores the thus-set turn radius R(n) inthe RAM.

On the other hand, when the smoothed yaw rate Ys(n) is smaller than orequal to the straight moving threshold Y0, the CPU determines “No” atthe step 1025 and then, executes a process of a step 1040 describedbelow. Thereafter, the CPU proceeds with the process to the step 1035.It should be noted that it is determined “No” at the step 1025 typicallywhen the own vehicle V stops temporarily at the center area of theintersection to wait for the oncoming vehicle, the walking person andthe like to pass the intersection after the right turn start conditionis satisfied or when the negative smoothed yaw rate Ys is calculated dueto a temporary left turning of the own vehicle V after the right turnstart condition is satisfied.

Step 1040: The CPU sets the turn radius R(n) to the turn radius R(c)acquired at the calculation cycle “c” as shown by the expression (13)and stores the thus-set turn radius R(n) in the RAM.

When the CPU proceeds with the process to the step 1035, the CPU setsthe value of the right turn flag XR to “1” and then, proceeds with theprocess to the step 695 of FIG. 6 via a step 1095 to terminate thisroutine once.

When the total turn angle θtotal(n) is larger than the turn end angleθend at a time of the CPU executing a process of the step 1020, the CPUdetermines “No” at the step 1020 and then, proceeds with the process toa step 1045 to set the value of the right turn flag XR to “0”.Thereafter, the CPU proceeds with the process to the step 695 of FIG. 6via the step 1095 to terminate this routine once.

When the right direction blinkers do not blink at a time of the CPUexecuting a process of the step 675 of FIG. 6, the CPU determines “No”at the step 675 and then, executes a process of a step 692 describedbelow. Thereafter, the CPU proceeds with the process to the step 695 toterminate this routine once.

Step 692: The CPU sets the value of the right turn waiting flag XRW to“0”.

Further, the CPU is configured or programmed to execute a routine shownby a flowchart in FIG. 11 each time the predetermined calculation timeTcal elapses. Therefore, at a predetermined timing, the CPU starts aprocess from a step 1100 of FIG. 11 and then, executes a process of astep 1105 described below. Thereafter, the CPU proceeds with the processto a step 1110.

Step 1105: The CPU calculates the turn center coordinates (Cx(n), Cy(n))on the basis of the turn radius R(n) as described above and stores thethus-calculated turn center coordinates (Cx(n), Cy(n)) in the RAM.

When the CPU proceeds with the process to the step 1110, the CPUdetermines whether the value of the left turn flag XL is “1”. When thevalue of the left turn flag XL is “1”, the CPU determines “Yes” at thestep 1110 and then, sequentially executes processes of steps 1115 to1125 described below. Thereafter, the CPU proceeds with the process to astep 1130.

Step 1115: The CPU calculates the left end turn radius RL(n) inaccordance with the expression (15) and the right end turn radius RR(n)in accordance with the expression (16) and stores the thus-calculatedleft and right end turning radii RL(n) and RR(n) in the RAM.

Step 1120: The CPU calculates the predicted left end route expressionfL(n) in accordance with the expression (19) and the predicted right endroute expression fR(n) in accordance with the expression (20) and storesthe thus-calculated predicted left and right end route expressions fL(n)and fR(n) in the RAM.

Step 1125: The CPU calculates the effective left end length LLe(n) inaccordance with the expression (22) and the effective right end lengthLRe(n) in accordance with the expression (23) and stores thethus-calculated effective left and right end lengths LLe(n) and LRe(n)in the RAM. In this regard, when the own vehicle V is in the left orright turn waiting state L1 or R1 and the smoothed yaw rate Ys(n) issmaller than or equal to the straight moving threshold Y0, the CPU setsthe effective left end length LLe(n) to a length up to 15 m from thevehicle left end OL(n) along the vehicle moving direction TD and setsthe effective right end length LRe(n) to a length up to 15 m from thevehicle right end OR(n) along the vehicle moving direction TD and storesthe thus-set effective left and right end lengths LLe(n) and LRe(n) inthe RAM.

On the other hand, when the value of the left turn flag XL is “0” at atime of the CPU executing a process of the step 1110, the CPU determines“No” at the step 1110 and then, proceeds with the process to a step 1135to determine whether the value of the right turn flag XR is “1”. Whenthe value of the right turn flag XR is “1”, the CPU determines “Yes” atthe step 1135 and then, sequentially executes a process of a step 1140described below and the processes of the steps 1120 and 1125.Thereafter, the CPU proceeds with the process to the step 1130.

Step 1140: The CPU calculates the left end turn radius RL(n) inaccordance with the expression (17) and the right end turn radius RR(n)in accordance with the expression (18) and stores the thus-calculatedleft and right end turning radii RL(n) and RR(n) in the RAM.

When the CPU proceeds with the process to the step 1130, the CPU isconfigured or programmed to execute a routine shown by a flowchart inFIG. 12. Therefore, when the CPU proceeds with the process to the step1130, the CPU starts a process from a step 1200 of FIG. 12 and then,sequentially executes processes of steps 1205 and 1210 described below.Thereafter, the CPU proceeds with the process to a step 1215. Thisroutine will be described in case that the object information on oneobject is acquired. In this regard, in case that the object informationon the objects is acquired, this routine is executed for the objectinformation on each of the objects.

Step 1205: The CPU acquires the object information on the objectexisting around the own vehicle V as the object information at thecalculation cycle “n” as described above and stores the thus-acquiredobject information in the RAM.

Step 1210: The CPU calculates the predicted route expression g(n) of theobject on the basis of the object information as described above andstores the thus-calculated predicted route expression g(n) in the RAM.

When the CPU proceeds with the process to the step 1215, the CPUdetermines whether the predicted route expression g(n) of the objectsatisfies the first crossing condition. When the predicted routeexpression g(n) of the object satisfies the first crossing condition,the CPU determines “Yes” at the step 1215 and then, sequentiallyexecutes processes of steps 1220 and 1225 described below. Thereafter,the CPU proceeds with the process to a step 1230.

Step 1220: The CPU calculates the coordinates of the point P(n) wherethe straight line expressed by the expression g(n) crosses the effectiveportion LRep(n) or LRep(n) of the predicted left or right end route asdescribed above and stores the thus-calculated coordinates in the RAM.

Step 1225: The CPU calculates a time predictively required for theobject to reach the point P(n) as the first time t1(n) as describedabove and stores the thus-calculated first time t1(n) in the RAM.

When the CPU proceeds with the process to the step 1230, the CPUdetermines whether the first time t1(n) is smaller than or equal to 4seconds, that is, whether the first time t1(n) satisfies the timecondition. When the first time t1(n) satisfies the time condition, theCPU determines “Yes” at the step 1230, that is, determines that there isthe target object and then, executes a process of a step 1235 describedbelow. Thereafter, the CPU proceeds with the process to a step 1195 ofFIG. 11 via a step 1295 to terminate this routine once.

Step 1235: The CPU sends a signal for performing the attention operationto the driver of the own vehicle V to the CPUs of the display ECU 20 andthe alert ECU 30. Thereby, the display device 21 and the buzzer 31perform the attention operation.

On the other hand, when the predicted route expression g(n) of theobject does not satisfy the first crossing condition, the CPU determines“No” at the step 1215, that is, determines that there is no targetobject and then, proceeds with the process to the step 1195 of FIG. 11via the step 1295 to terminate this routine once.

When the first time t1(n) does not satisfy the time condition, the CPUdetermines “No” at the step 1230, that is, determines that there is notarget object and then, proceeds with the process to the step 1195 ofFIG. 11 via the step 1295 to terminate this routine once.

The concrete operation of the first embodiment apparatus has beendescribed. The first embodiment apparatus determines whether each of theleft and right turn waiting conditions and the left and right turn startconditions is satisfied on the basis of the own vehicle informationacquired by the various sensors installed in the own vehicle V. Thus,even when the position of the own vehicle V cannot be estimated by aGNSS (i.e., Global Navigation Satellite System) and/or wirelesscommunication, the first embodiment apparatus can accurately determinewhether the own vehicle V is turning left or right in the intersectionon the basis of the own vehicle information.

In addition, the first embodiment apparatus calculates the effectiveleft end length LLe, using a value based on a product of the remainingturn angle θre (=90°−θtotal) and the left end turn radius RL and theeffective right end length LRe, using a value based on a product of theremaining turn angle θre and the right end turn radius RR. In otherwords, the effective left end length LLe is a length of an arc of thecircle expressed by the predicted left end route expression fLcorresponding to the remaining turn angle θre (=90°−θtotal) and theeffective right end length LRe is a length of an arc of the circleexpressed by the predicted right end route expression fR correspondingto the remaining turn angle θre.

In particular, according to the first embodiment apparatus, theeffective left and right end lengths LLe and LRe are calculated on thebasis of the total turn angle θtotal and the effective left and rightend lengths LLe and LRe decreases as the total turn angle θtotalincreases, that is, the left or right turning of the own vehicle V inthe intersection, proceeds. Thus, the effective portions LLep and LRepof the predicted routes are unlikely to exceed a lane on which the ownvehicle V is moving and reach a lane opposite to the lane on which theown vehicle V is moving or a curb along the lane opposite to the lane onwhich the own vehicle V is moving. Thereby, the unnecessary attentionoperation to the driver is unlikely to be performed and the attentionoperation to the driver is appropriately performed when the own vehicleV is in the left or right turn state in the intersection even though theposition of the own vehicle V cannot be estimated by the GNSS and/or thewireless communication.

Especially, according to the first embodiment apparatus, the predictedleft end route corresponding to the predicted route of the vehicle leftend OL and the predicted right end route corresponding to the predictedroute of the vehicle right end OR are estimated, respectively. Thepredicted left and right end routes define boundaries of area where abody of the own vehicle V is predicted to pass. Thus, the predictedroute approximate to the actual moving route of the own vehicle V can beestimated, for example, compared with a case that a route which thevehicle base point O (i.e., the center of the own vehicle V in thevehicle width) is predicted to pass, is estimated as the predictedroute. As a result, it can be accurately determined whether theattention operation to the driver should be performed. In addition, theleft end turn radius RL is used as an estimated turn radius forcalculating the effective left end length LLe of the predicted route andthe right end turn radius RR is used as the estimated turn radius forcalculating the effective right end length LRe of the predicted route.Thus, the effective left and right end lengths LLe and LRe can beappropriately calculated. With this configuration, it can be accuratelydetermined whether the attention operation to the driver should beperformed.

Further, when the driver starts to turn the own vehicle V left or right,the driver generally operates the blinker lever after the driverdecelerates the own vehicle V such that the vehicle speed SPD decreasesto a speed suitable to start to turn the own vehicle V left or right(i.e., a first vehicle speed SPD1≤SPD≤a second vehicle speed SPD2).Otherwise, when the driver starts to turn the own vehicle V left orright, the driver generally operates the blinker lever and then,decreases the vehicle speed SPD to the speed suitable to start to turnthe own vehicle v left or right. Otherwise, when the driver starts toturn the own vehicle V left or right, the driver operates the blinkerlever while decreasing the vehicle speed SPD to the speed suitable tostart to turn the own vehicle V left or right. The first embodimentapparatus uses the left turn waiting conditions LW1 to LW3 or the rightturn waiting conditions RW1 to RW3 for determining whether the ownvehicle V is set to turn left or right. Thus, it can be appropriatelydetermined whether the own vehicle V is set to turn left or right, thatis, whether the driver intends to start to turn the own vehicle V leftor right.

Further, when the first embodiment apparatus determines that the leftturn start conditions LS1 to LS6 are first satisfied while the leftdirection blinkers are blinking after the own vehicle V is set to turnleft, that is, the left turn waiting condition is satisfied, the firstembodiment apparatus determines that the own vehicle V starts to turnleft, that is, the left turn start condition is satisfied. Similarly,when the first embodiment apparatus determines that the right turn startconditions RS1 to RS6 are first satisfied while the right directionblinkers are blinking after the own vehicle V is set to turn right, thatis, the right turn waiting condition is satisfied, the first embodimentapparatus determines that the own vehicle V starts to turn right, thatis, the right turn start condition is satisfied. Therefore, it can beappropriately determined whether the own vehicle V starts to turn leftor right when the first embodiment apparatus does not haveself-position-estimation function, using the GNSS and/or the wirelesscommunication or the first embodiment apparatus cannot use theself-position-estimation function even though the first embodimentapparatus has the self-position-estimation function.

Further, the first embodiment apparatus calculates the first time t1only when the straight line expressed by the expression g (hereinafter,the straight line expressed by the expression g will be referred to as“the straight line gL”) crosses any of the effective portions LLep andLRep of the predicted routes. Therefore, the first embodiment apparatusdoes not calculate the first time t1 when the straight line gL does notcross the effective portions LLep and LRep of the predicted routes.Thus, a processing time can be decreased. Further, when the firstcrossing points is two, the first embodiment apparatus calculates thefirst time t1 only for the first crossing point which the straight linegL first crosses any of the effective portions LLep and LRep of thepredicted routes in the moving direction of the object. Thus, it can beearly determined whether the object crosses any of the effectiveportions LLep and LRep of the predicted routes, compared with a casethat the first embodiment apparatus calculates the first time t1 for thefirst crossing points which the straight line gL first crosses theeffective portions LLep and LRep of the predicted routes, respectivelyin the moving direction of the object. Therefore, the attentionoperation to the driver can be appropriately performed.

Further, according to the first embodiment apparatus, the left end turnradius RL for the left turning is “R−W/2” and the right end turn radiusRL for the right turning is “R+W/2”. On the other hand, the right endturn radius RR for the left turning is “R+W/2” and the right end turnradius RR for the right turning is “R−W/2”. Thus, the left and right endturn radii RL and RR can be appropriately calculated when the ownvehicle V turns left as well as when the own vehicle V turns right.

Further, an angle defined between a vehicle axis of the own vehicle V(i.e., a center axis of the own vehicle V in a longitudinal direction ofthe own vehicle V) before the own vehicle V starts to turn left or rightand the vehicle axis of the own vehicle V when the own vehicle Vcompletes the left or right turning, is about 90° for the typicalintersection. The first embodiment apparatus sets 90° as the turn endangle θend used for calculating the remaining turn angle θre. Thus, theeffective left and right end lengths LLe and LRe are generally equal tothe lengths of the predicted routes from the present position of the ownvehicle V to a position where the own vehicle V completes the left orright turning. Therefore, the attention operation to the driver can beappropriately performed.

Further, the first embodiment apparatus initializes the total turn angleθtotal only when the first embodiment apparatus determines that the ownvehicle V is set to turn left or right and thereafter, does notinitialize the total turn angle θtotal until the own vehicle V completesthe left or right turning. Thus, the total turn angle θtotal is notinitialized while the own vehicle V is turning left or right in theintersection. Therefore, the total turn angle θtotal used forcalculating the remaining turn angle θre can be appropriatelycalculated.

Modified Example

<Summary of Operation of Modified Apparatus>

Next, a driving assist apparatus of the vehicle according to a modifiedexample of the first embodiment will be described. Hereinafter, thedriving assist apparatus according to the modified example will bereferred to as “the modified apparatus”. When the smoothed yaw rateYs(n) is larger than the straight moving threshold Y0 (=10⁻⁶), the firstembodiment apparatus calculates the predicted routes at the calculationcycle “n” on the basis of the turn radius R(n) calculated, using thesmoothed yaw rate Ys(n) in accordance with the expression (11) (i.e.,R(n)=SPD(n)/Ys(n)). Therefore, for example, if the smoothed yaw rate Ysis larger than the straight moving threshold Y0 when the own vehicle Vis set to turn left, the first embodiment apparatus acquires thepredicted routes on the basis of the turn radius R calculated, using thesmoothed yaw rate Ys acquired when the own vehicle V is set to turnleft.

In this regard, when the driver turns the own vehicle V left, ingeneral, the driver first rotates the steering wheel 14 a to increasethe steering angle θsw. After the steering angle θsw reaches a maximumsteering angle, the driver maintains the steering angle θsw at themaximum steering angle for a while. Then, the driver decreases thesteering angle θsw. When the steering angle θsw becomes zero, the drivercompletes the left turning.

Therefore, a period of the left turning of the own vehicle V includes asteering angle increase period and a steering angle decrease period. Thesteering angle increase period corresponds to a period from a time whenthe driver starts to rotate the steering wheel 14 a, that is, the ownvehicle V starts to turn left to a time immediately before the steeringangle θsw reaches the maximum steering angle. The steering angledecrease period corresponds to a period from a time when the steeringangle θsw reaches the maximum steering angle to a time when the steeringangle θsw becomes zero.

The smoothed yaw rate Ys acquired in the steering angle increase periodis larger than the smoothed yaw rate Ys acquired when the steering angleθsw is the maximum steering angle. Therefore, when the turn radius R iscalculated, using the smoothed yaw rate Ys in the steering angleincrease period, the calculated turn radius R is larger than the turnradius R calculated, using the smoothed yaw rate Ys acquired when thesteering angle θsw is the maximum steering angle. Thus, when thepredicted routes are calculated, using the turn radius R calculated inthe steering angle increase period, the predicted routes depart from theactual moving routes of the own vehicle V and therefore, the appropriateattention operation to the driver may not be performed.

The inventors of this application have studied aforementioned matters.As a result, the inventors have realized that the predicted routeapproximate to the actual moving route of the own vehicle V can beacquired in the steering angle increase period and an accuracy of theattention operation to the driver can be improved by calculating theturn radius R, using an estimated yaw rate Yest described below withoutusing the present smoothed yaw rate Ys and acquiring the predicted routeon the basis of the thus-calculated turn radius R.

In this regard, the inventors of this application define the steeringangle increase period as a period until the total turn angle θtotal ofthe own vehicle V reaches the total turn angle θtotal corresponding tothe maximum steering angle θsw. In the modified example, the total turnangle θtotal corresponding to the maximum steering angle θsw is 45°.Hereinafter, the total turn angle θtotal corresponding to the maximumsteering angle θsw will be referred to as “the steering switch angleθth”. In consideration of a result of an experiment, the steering switchangle θth may be set to an appropriate value larger than 0° and smallerthan 90°.

<Steering Angle Increase Period>

When a change amount ΔYs of the smoothed yaw rate Ys is larger than zero(hereinafter, this case will be referred to as “the case A1”), themodified apparatus calculates an estimated yaw rate Yest as describedbelow.

The modified apparatus presumes that the smoothed yaw rate Ys continuesto increase by the present change amount ΔYs of the present smoothed yawrate Ys. In particular, the present change amount ΔYs of the smoothedyaw rate Ys is a temporal differentiation value of the smoothed yaw rateYs and hereinafter, will be referred to as “the smoothed yaw rate changeamount ΔYs”. The modified apparatus calculates, as a required time Treq,a time required for the own vehicle V to turn by a steering switchremaining angle Δθ obtained by subtracting the present turn angle θtotalfrom the steering switch angle θth (Δθ=θth−θtotal).

Then, the modified apparatus calculates the estimated yaw rate Yest bydividing the steering switch remaining angle Δθ by the required timeTreq (Yest=Δθ/Treq). Therefore, the estimated yaw rate Yest is anaverage of the yaw rates Y acquired when the own vehicle V turns bysteering switch remaining angle Δθ for the required time Treq. Themodified apparatus sets the turn radius R to a first estimated turnradius Rest1 corresponding to the turn radius calculated, using theestimated yaw rate Yest. Further, the modified apparatus estimates thepredicted routes on the basis of the thus-set turn radius R.

The estimated yaw rate Yest is calculated on the presumption that thesmoothed yaw rate Ys continues to increase by the present smoothed yawrate change amount ΔYs. Thus, the estimated yaw rate Yest is larger thanthe present smoothed yaw rate Ys. Therefore, the turn radius Rcalculated, using the estimated yaw rate Yest is smaller than the turnradius R calculated, using the present smoothed yaw rate Ys. As aresult, the modified apparatus can acquire the predicted routesapproximate to the actual moving route of the own vehicle V. Thus, themodified apparatus can appropriately perform the attention operation tothe driver.

In this regard, as described later, when the estimated yaw rate Yest issmaller than or equal to the straight moving threshold Y0 (in themodified example, 10⁻⁶), the modified apparatus estimates the predictedroutes, using the turn radius R set to the straight line equivalentvalue Rc (=12700 m) without using the turn radius R calculated, usingthe estimated yaw rate Yest.

<Case A2>

As described above, the modified apparatus presumes that the presentsmoothed yaw rate change amount ΔYs in the steering angle increaseperiod is larger than zero. Therefore, when the present smoothed yawrate ΔYs in the steering angle increase period is smaller than or equalto zero, that is, the present smoothed yaw rate Vs decreases or does notchange, the estimated yaw rate Yest calculated by a calculation methoddescribed above for the case A1 is smaller than or equal to the presentsmoothed yaw rate Ys. Thus, the predicted routes acquired on the basisof the turn radius R calculated, using the estimated yaw rate Yestcalculated by the calculation method described above for the case A1,departs from the actual moving route of the own vehicle V.

Accordingly, when the present smoothed yaw rate change amount ΔYs in thesteering angle increase period is smaller than or equal to zero(hereinafter, this case will be referred to as “the case A2”), themodified apparatus calculates the estimated yaw rate Yest as describedbelow.

When the present smoothed yaw rate change amount ΔYs in the steeringangle increase period is smaller than or equal to zero and there is thesmoothed yaw rate change amount ΔYs larger than zero before the presentcalculation cycle, the modified apparatus presumes that the smoothed yawrate Ys continues to increase by the smoothed yaw rate change amount ΔYswhich is larger than zero and is acquired at the last calculation cycle.Then, the modified apparatus calculates the estimated yaw rate Yest bythe same calculation method as the calculation method described abovefor the case A1. Then, the modified apparatus sets the turn radius R tothe first estimated turn radius Rest1. Then, the modified apparatusacquires the predicted routes on the basis of the thus-set turn radiusR.

The thus-calculated estimated yaw rate Yest is larger than the presentsmoothed yaw rate Ys. Thus, the modified apparatus can acquire thepredicted routes approximate to the actual moving route of the ownvehicle V.

In this regard, as described later, when the estimated yaw rate Yest issmaller than or equal to the straight moving threshold Y0 (in themodified example, 10⁻⁶), the modified apparatus acquires the predictedroutes, using the turn radius R set to the straight line equivalentvalue Rc (=12700 m) without using the turn radius R calculated, usingthe estimated yaw rate Yest.

<Case A3>

Further, when the present smoothed yaw rate change amount ΔYs in thesteering angle increase period is smaller than or equal to zero, thereis no smoothed yaw rate change amount ΔYs larger than zero before thepresent calculation cycle and the present smoothed yaw rate Ys is largerthan the straight moving threshold Y0 (hereinafter, this case will bereferred to as “the case A3”), the modified apparatus acquires thepredicted routes on the basis of the turn radius R calculated, using thepresent smoothed yaw rate Ys.

<Case A4>

Further, when the present smoothed yaw rate change amount ΔYs in thesteering angle increase period is smaller than or equal to zero, thereis no smoothed yaw rate change amount ΔYs larger than zero before thepresent calculation cycle and the present smoothed yaw rate Ys issmaller than or equal to the straight moving threshold Y0 (hereinafter,this case will be referred to as “the case A4”), the modified apparatusacquires the predicted routes, using the turn radius R set to thestraight line equivalent value Rc (=12700 m) without using the turnradius R calculated, using the present smoothed yaw rate Ys as describedlater.

<Steering Angle Decrease Period>

The steering angle θsw gradually decreases in the steering angledecrease period following the steering angle increase period, that is,in a period after the total turn angle θtotal of the own vehicle Vbecomes larger than or equal to the steering switch angle θth. Thus, thesmoothed yaw rate Ys also gradually decreases. Therefore, when thepredicted routes are acquired, using the turn radius R calculated, usingthe present smoothed yaw rate Ys, the thus-acquired predicted routesdepart from the actual moving route of the own vehicle V.

The inventors of this application have studied aforementioned matters.As a result, the inventors have realized that the predicted routeapproximate to the actual moving route can be acquired in the steeringangle decrease period by acquiring the predicted route on the basis ofthe turn radius of the own vehicle V (i.e., a second estimated turnradius Rest2 described below), presuming that the own vehicle Vcontinues to turn at a rate of the estimated yaw rate Yest acquiredimmediately before the steering angle increase period ends.

In this regard, similar to the case A1, when the estimated yaw rate Yestis smaller than or equal to the straight moving threshold Y0, themodified apparatus acquires the predicted routes, using the turn radiusR set to the straight line equivalent value Rc (=12700 m) without usingthe turn radius R calculated, using the estimated yaw rate Yest asdescribed later.

It should be noted that when the calculation cycle immediately beforethe total turn angle θtotal reaches the steering switch angle θth isdefined as the calculation cycle “m”, the estimated yaw rate Yestimmediately before the end of the steering angle increase period is theestimated yaw rate Yest(m) acquired at the calculation cycle “m”.

As can be understood from the description for the case A3, when there isno smoothed yaw rate change amount ΔYs larger than zero in the steeringangle increase period, the estimated yaw rate Yest is not calculated. Inthis case, the modified apparatus acquires the predicted routes on thebasis of the turn radius R calculated, using the smoothed yaw rate Ys(m)acquired at the calculation cycle “m” in place of the estimated yaw rateYest.

The steering angle θsw gradually decreases in the steering angledecrease period. Thus, the smoothed yaw rate Ys(m) acquired at thecalculation cycle “m” is larger than the smoothed yaw rate Ys acquiredin the steering angle decrease period. As described above, the modifiedapparatus acquires the predicted routes on the basis of the smoothed yawrate Ys(m) acquired at the calculation cycle “m” in the steering angledecrease period. Therefore, the modified apparatus can acquire thepredicted routes approximate to the actual moving route of the ownvehicle V, compared with a case that the predicted routes are acquiredon the basis of the present smoothed yaw rate Ys.

In this regard, as described later, when the smoothed yaw rate Ys(m)acquired at the calculation cycle “m” is smaller than or equal to thestraight moving threshold Y0, the modified apparatus acquires thepredicted routes, using the turn radius R set to the straight lineequivalent value Rc without using the turn radius R calculated, usingthe smoothed yaw rate Ys(m).

Hereinafter, the turn radius R calculated in the steering angle decreaseperiod will be referred to as “the second estimated turn radius Rest2”.

The modified apparatus sets the turn radius R and acquires the predictedroutes on the basis of the turn radius R by the same method as themethod described for the cases A1 to A3 when the own vehicle V turnsright.

Further, the modified apparatus sets the turn radius R and acquires thepredicted routes on the basis of the turn radius R by the same method asthe method described for the cases A1 to A3 when the own vehicle V turnsleft. In particular, once the left turn waiting condition is satisfied,the modified apparatus acquires the predicted routes as far as the leftdirection blinkers are in the blinking state or the total turn angleθtotal is smaller than or equal to the turn end angle θend (=90°). Thus,the modified apparatus does not determine whether the own vehicle V isin the left turn state, that is, the left turn start condition issatisfied. This is applied to the case that the own vehicle V turnsright.

A summary of an operation of the modified apparatus has been described.Below, the operation of the modified apparatus, in particular, adifference between the operation of the modified apparatus and theoperation of the first embodiment apparatus will be described in detail.

<Calculation of Smoothed Yaw Rate Change Amount ΔYs>

In the steering angle increase period, that is, a period which the totalturn angle θtotal is smaller than the steering switch angle θth (=45°),the modified apparatus sets the smoothed yaw rate change amount ΔYs(0)corresponding to the calculation cycle “0” (n=0) as shown by anexpression (24) described below for calculating any of the firstestimated turn radius Rest1, the turn radius R and the second estimatedturn radius Rest2 necessary to acquire the predicted routes approximateto the actual moving route of the own vehicle V.ΔYs(0)=0  (24)

Thereafter (n≥1), the modified apparatus calculates, as the smoothed yawrate change amount ΔYs(n) after the calculation cycle “1”, a changeamount of the smoothed yaw rate Ys(n) acquired at the calculation cycle“n” with respect to the smoothed yaw rate Ys(n−1) acquired at thecalculation cycle “n−1” in accordance with an expression (25) describedbelow. In this regard, the predetermined calculation time Tcal isextremely small. Thus, the smoothed yaw rate change amount ΔYs(n) can besubstantially the same as the temporal differentiation value dYs(n)/dtof the smoothed yaw rate Ys(n).ΔYs(n)=Ys(n)−Ys(n−1)  (25)

On the other hand, in the steering angle decrease period, the modifiedapparatus does not calculate the smoothed yaw rate change amount ΔYs.

<Calculation of Converted Value ΔYsc of Smoothed Yaw Rate Change AmountΔYs>

As described above, the modified apparatus uses the calculation methodof the turn radius R, depending on the smoothed yaw rate change amountΔYs. If describing the modified apparatus using the smoothed yaw ratechange amount ΔYs, the description will be complicated. Accordingly, forsimplifying the description, a converted value ΔYsc corresponding to avalue obtained by converting the smoothed yaw rate change amount ΔYs,will be used. The converted value ΔYsc is calculated as described below.

When the smoothed yaw rate change amount ΔYs(n) is larger than zero, themodified apparatus sets the smoothed yaw rate change amount ΔYs(n) asthe converted value ΔYsc(n) as shown by an expression (26) describedbelow.ΔYsc(n)=ΔYs(n)  (26)

Further, the last calculation cycle among the calculation cycles “i” atwhich the smoothed yaw rate change amount ΔYs larger than zero beforethe present calculation cycle “n”, will be referred to as “thecalculation cycle “c””. When the smoothed yaw rate change amount ΔYs(n)is smaller than or equal to zero and the smoothed yaw rate changeamount(s) ΔYs larger than zero is/are acquired at the calculationcycle(s) “i” before the present calculation cycle “n”, the modifiedapparatus sets the smoothed yaw rate change amount ΔYs(e) acquired atthe calculation cycle “e” as the converted value ΔYsc(n) as shown by anexpression (27) described below.ΔYsc(n)=ΔYs(e)  (27)

On the other hand, when the smoothed yaw rate change amount ΔYs(n) issmaller than or equal to zero and the smoothed yaw rate change amountΔYs larger than zero has not been acquired at the calculation cycle “i”before the present calculation cycle “n”, the modified apparatus setsthe converted value ΔYsc(n) to zero as shown by an expression (28)described below.ΔYsc(n)=0  (28)

The modified apparatus calculates any of the first estimated turn radiusRest1, the turn radius R and the second estimated turn radius Rest2,depending on cases described below.

<Case that θtotal(n)<θth and ΔYsc(n)>0>

<Calculation of Required Time Treq>

When the total turn angle θtotal is smaller than the steering switchangle θth (=45°) and the present converted value ΔYsc(n) is larger thanzero, that is, when the present converted value ΔYsc(n) is larger thanzero in the steering angle increase period, the modified apparatuspresumes that the smoothed yaw rate Ys continues to increase at a rateof the converted value ΔYsc(n). In this case, the modified apparatuscalculates the required time Treq(n) required for the own vehicle V toturn by a steering switch remaining angle Δθ(n) (=45°−θtotal(n)) inaccordance with an expression (32) described below.

The expression (32) is acquired as described below. When the total turnangle θtotal is smaller than the steering switch angle θth (=45°), thepresent converted value ΔYsc(n) is larger than zero and the smoothed yawrate Ys continues to increase at a rate of the converted value ΔYsc(n),an expression (29) described below is established. Then, an expression(30) described below is acquired by changing the expression (29). Then,an expression (31) described below is acquired by changing theexpression (30). Then, an expression (32) described below is acquired bysolving the expression (31), regarding the required time Treq(n). Theconverted value ΔYsc(n) of the expression (29) is the converted valuecorresponding to the smoothed yaw rate change amount ΔYs(n), that is,the temporal differentiation value dYs(n)/dt.θth=θtotal(n)+∫₀ ^(Treq(n))(Ys(n)+ΔYsc(n)×t)dt  (29)ΔYsc(n)×Treq(n)²/2+Ys(n)×Treq(n)−(θth−θtotal(n))=0  (30)ΔYsc(n)×Treq(n)²+2×Ys(n)×Treq(n)−2×(θth−θtotal(n))=0  (31)Treq(n)=(−Ys(n)+√{square root over((Ys(n)²+2×ΔYsc(n)×(θth−θtotal(n)))))}/ΔYsc(n)  (32)

The modified apparatus assigns the steering switch angle θth (=45°), thetotal turn angle θtotal(n), the smoothed yaw rate Ys(n) and theconverted value ΔYsc(n) to the expression (32) to calculate the requiredtime Treq(n).

<Calculation of Estimated Yaw Rate Yest>

In addition, the modified apparatus calculates the steering switchremaining angle Δθ(n) (=θth−θtotal(n)). The modified apparatus assignsthe thus-calculated steering switch remaining angle Δθ(n) and therequired time Treq(n) to an expression (33) described below to calculatethe estimated yaw rate Yest(n) while the total turn angle θtotal(n) issmaller than the steering switch angle θth. That is, the modifiedapparatus calculates, as the estimated yaw rate Yest(n), an average ofthe yaw rates Y acquired far the own vehicle V to turn by the steeringswitch remaining angle Δθ(n) for the required time Treq(n).Yest(n)=Δθ(n)/Treq(n)  (33)

<Calculation of First Estimated Turning Radius Rest1>

When the estimated yaw rate Yest(n) is larger than the straight movingthreshold Y0, the modified apparatus calculates, as the first estimatedturn radius Rest1(n), a value obtained by dividing the vehicle speedSPD(n) by the estimated yaw rate Yest(n) in place of the smoothed yawrate Ys(n) as shown by an expression (34) described below. The modifiedapparatus sets the first estimated turn radius Rest1(n) as the turnradius R(n). The straight moving threshold Y0 is a threshold foravoiding that the first estimated turn radius Rest1(n) calculated bydividing the vehicle speed SPD(n) by the estimated yaw rate Yest(n)close to zero, is excessively large. In the modified example, thestraight moving threshold Y0 is 10⁻⁶.Rest1(n)=SPD(n)/Yest(n)  (34)

Further, for example, when the own vehicle V moves generally straight atthe intersection, the smoothed yaw rate Ye and the converted value ΔYscare considerably small. Therefore, the required time Treq calculated inaccordance with the expression (32) is considerably large and as aresult, the estimated yaw rate Yest calculated in accordance with theexpression (33) is about zero. In this case, the first estimated turnradius Rest1(n) calculated in accordance with the expression (34) isexcessively large and thus, the processing load of the CPU may be large.

Accordingly, when the estimated yaw rate Yest is smaller than or equalto the straight moving threshold Y0, the modified apparatus sets thefirst estimated turn radius Rest1(n) to the straight line equivalentvalue Rc (=12700 m) as shown by an expression (35) described below inplace of the expression (34).Rest1(n)=Rc=12700 m  (35)

<Case that θtotal<θth and ΔYsc(n)=0>

<Calculation of Turn Radius>

As shown by the expression (28), when all of the smoothed yaw ratechange amounts ΔYs acquired before the present calculation cycle “n” aresmaller than or equal to zero, and as a result, the present convertedvalue ΔYsc(n) is zero and the smoothed yaw rate Ys(n) is larger than thestraight moving threshold Y0, the modified apparatus sets a valuecalculated by dividing the vehicle speed SPD(n) by the smoothed yaw rateYs(n) as the turn radius R(n) as shown by an expression (36) describedbelow.R(n)=SPD(n)/Ys(n)  (36)

The inventors of this application have had a knowledge that theattention operation to the driver can be appropriately performed, usingthe generally straight lines as the predicted routes in the intersectionwhen the smoothed yaw rate Ys(n) is smaller than or equal to thestraight moving threshold Y0 (=10⁻⁶).

Accordingly, when the present converted value ΔYsc(n) is zero and thesmoothed yaw rate Ys(n) is smaller than or equal to the straight movingthreshold Y0 in the steering angle increase period, the modifiedapparatus sets the straight line equivalent value Rc (=12700 m) as theturn radius R(n) as shown by an expression (37) described below.Thereby, the shapes of the predicted routes in the intersection becomethe generally straight lines, respectively.R(n)=Rc=12700 m  (37)

It should be noted that the smoothed yaw rate Ys(n) is smaller than orequal to the straight moving threshold Y0 typically when the own vehicleV stops temporarily or when the own vehicle V moves straight or when thenegative smoothed yaw rate Ys is calculated due to the turning of theown vehicle V in a direction opposite to an attempted left or rightturning direction of the own vehicle V.

<Calculation of Second Estimated Turning Radius Rest2>

The modified apparatus calculates the second estimated turn radius Rest2in the steering angle decrease period as described below.

In the steering angle decrease period after the total turn angle θtotalreaches the steering switch angle θth (=45°), the steering angle θswgradually decreases. Thus, the smoothed yaw rate Ys decreases.Accordingly, in the steering angle decrease period, the modifiedapparatus presumes that the own vehicle V continues to turn at a rate ofthe estimated yaw rate Yest(m) calculated at the calculation cycle “m”immediately before the total turn angle θtotal reaches the steeringswitch angle θth.

In this regard, as described above, the modified apparatus calculatesthe estimated yaw rate Yest only when the converted value ΔYsc is largerthan zero. Thus, when the converted value ΔYsc is zero, the modifiedapparatus presumes that the own vehicle V continues to turn at a rate ofthe smoothed yaw rate Ys(m) calculated at the calculation cycle “m” inplace of the estimated yaw rate Yest(m) calculated at the calculationcycle “m”.

That is, when the converted value ΔYsc(m) calculated at the calculationcycle “m” is larger than zero and the estimated yaw rate Yest(m)calculated at the calculation cycle “m” is larger than the straightmoving threshold Y0 (=10⁻⁶), the modified apparatus calculates thesecond estimated turn radius Rest2(n) by dividing the vehicle speedSPD(n) by the estimated yaw rate Yest(m) calculated at the calculationcycle “m” as shown by an expression (38) described below. Then, themodified apparatus sets the thus-calculated second estimated turn radiusRest2(n) as the turn radius R(n).Rest2(n)=SPD(n)/Yest(m)  (38)

Further, when the estimated yaw rate Yest(m) calculated at thecalculation cycle “m” is smaller than or equal to the straight movingthreshold Y0, the modified apparatus sets the straight line equivalentvalue Rc (=12700 m) as the second estimated turn radius Rest2(n) asshown by an expression (39) described below. Then, the modifiedapparatus sets the thus-set second estimated turn radius Rest2(n) as theturn radius R(n).Rest2(n)=Rc=12700 m  (39)

Further, when the converted value ΔYsc(m) calculated at the calculationcycle “m” is zero, that is, all of the smoothed yaw rate change amountsΔYs calculated in the steering angle decrease period are smaller than orequal to zero and the smoothed yaw rate Ys(m) calculated at thecalculation cycle “m” is larger than the straight moving threshold Y0,the modified apparatus calculates the second estimated turn radiusRest2(n) by dividing the vehicle speed SPD(n) by the smoothed yaw rateYs(m) calculated at the calculation cycle “m” as shown by an expression(40) described below. Then, the modified apparatus sets thethus-calculated second estimated turn radius Rest2(n) as the turn radiusR(n).Rest2(n)=SPD(n)/Ys(m)  (40)

Further, when the converted value ΔYsc(m) calculated at the calculationcycle “m” is zero and the smoothed yaw rate Ys(m) calculated at thecalculation cycle “m” is smaller than or equal to the straight movingthreshold Y0, the modified apparatus sets the straight line equivalentvalue Rc (=12700 m) as the second estimated turn radius Rest2(n) asshown by an expression (41) described below. Then, the modifiedapparatus sets the thus-set second estimated turn radius Rest2(n) as theturn radius R(n).Rest2(n)=Rc=12700 m  (41)

The modified apparatus calculates the predicted route expressions fL(n)and fR(n) on the basis of the thus-set turn radius R(n) by a methodsimilar to a method of the first embodiment apparatus for calculatingthe predicted route expressions fL(n) and fR(n).

When the own vehicle V is set to turn right, the modified apparatus setsthe turn radius R(n) similar to when the own vehicle V is set to turnleft.

<Concrete Operation of Modified Apparatus>

Below, a concrete operation of the modified apparatus will be described.The CPU of the driving assist ECU 10 of the modified apparatus isconfigured or programmed to execute a routine shown by a flowchart inFIG. 13 each time the predetermined calculation time Tcal elapses.Therefore, at a predetermined timing, the CPU starts a process from astep 1300 of FIG. 13 and then, proceeds with the process to a step 1305to acquire the own vehicle information.

Then, the CPU proceeds with the process to a step 1310 to determinewhether the left turn waiting condition is satisfied on the basis of theown vehicle information. When the left turn waiting condition issatisfied, that is, the CPU determines that the own vehicle V is set toturn left, the CPU determines “Yes” at the step 1310 and then,sequentially executes processes of steps 1315 to 1335 described below.Thereafter, the CPU proceeds with the process to a step 1340.

Step 1315: The CPU sets the total turn angle θtotal to 0°, that is,initializes the total turn angle θtotal.

Step 1320: The CPU sets the value of the left turn flag XL to “1” andthe value of the right turn flag XR to “0”.

Step 1325: The CPU calculates the smoothed yaw rate Ys(n) in accordancewith any of the expressions (1L), (2L), (3), (4), (5L) and (6L) when thevalue of the left turn flag XL is “1”. On the other hand, the CPUcalculates the smoothed yaw rate Ys(n) in accordance with any of theexpressions (1R), (2R), (3), (4), (5R) and (6R) when the value of theright turn flag XR is “1”.

Step 1330: The CPU calculates the instantaneous turn angle θ(n) inaccordance with any of the expressions (7) and (8).

Step 1335: The CPU calculates the total turn angle θtotal(n) inaccordance with any of the expressions (9) and (10).

On the other hand, when the left turn waiting condition is not satisfiedat a time of the CPU executing a process of the step 1310, the CPUdetermines “No” at the step 1310 and then, proceeds with the process toa step 1360 to determine whether the left direction blinkers areblinking. It should be noted that it is determined “No” at the step 1310when a determination process of the step 1310 is executed after it isfirst determined that the left turn waiting condition is satisfied afterit is determined last time that the left or right turning is completedor when the left turn waiting condition has not been satisfied after itis determined last time that the left or right turning is completed.

When the CPU executes the determination process of the step 1310 afterthe CPU first determines that the left turn waiting condition issatisfied after the CPU determines last time that the left or rightturning of the own vehicle V is completed, the CPU determines “No” atthe step 1310. In this case, when the driver has an attempt to turn theown vehicle V left and thus, causes the left direction blinkers toblink, the CPU determines “Yes” at the step 1360 and then, sequentiallyexecutes the processes of the steps 1320 to 1335 described above.Thereafter, the CPU proceeds with the process to the step 1340.

When the left direction blinkers do not blink at a time of the CPUexecuting a process of the step 1360, the CPU determines “No” at thestep 1360 and then, proceeds with the process to a step 1365 todetermine whether the right turn waiting condition is satisfied on thebasis of the own vehicle information.

When the right turn waiting condition is satisfied, that is, the CPUdetermines that the own vehicle V is set to turn right, the CPUdetermines “Yes” at the step 1365 and then, sequentially executesprocesses of steps 1370 and 1375 described below and the processes ofthe steps 1325 to 1335 described above. Thereafter, the CPU proceedswith the process to the step 1340.

Step 1370: The CPU sets the total turn angle θtotal to 0°, that is,initializes the total turn angle θtotal.

Step 1375: The CPU sets the value of the left turn flag XL to “0” andthe value of the right turn flag XR to “1”.

On the other hand, when the right turn waiting condition is notsatisfied at a time of the CPU executing a process of the step 1365, theCPU determines “No” at the step 1365 and then, proceeds with the processto a step 1380 to determine whether the right direction blinkers areblinking. It should be noted that it is determined “No” at the step 1365when a determination process of the step 1365 is executed after it isfirst determined that the right turn waiting condition is satisfiedafter it is determined last time that the left or right turning iscompleted or when the right turn waiting condition has not beensatisfied after it is determined last time that the left or rightturning is completed.

When the CPU executes the determination process of the step 1365 afterthe CPU first determines that the right turn waiting condition issatisfied after the CPU determines last time that the left or rightturning of the own vehicle V is completed, the CPU determines “No” atthe step 1365. In this case, when the driver has an attempt to turn theown vehicle V right and thus, causes the right direction blinkers toblink, the CPU determines “Yes” at the step 1380 and then, sequentiallyexecutes the processes of the steps 1375 and 1325 to 1335 describedabove. Thereafter, the CPU proceeds with the process to the step 1340.

When the right direction blinkers do not blink, that is, the rightdirection blinkers are in the non-blinking state, the CPU determines“No” at the step 1380 and then, proceeds with the process to a step 1395to terminate this routine once.

When the CPU proceeds with the process to the step 1340, the CPUdetermines whether the total turn angle θtotal(n) is smaller than orequal to the turn end angle θend (=90°). When the total turn angleθtotal(n) is smaller than or equal to the turn end angle θend, the CPUdetermines “Yes” at the step 1340, that is, the CPU determines that theown vehicle V turns left, the CPU proceeds with the process to a step1345 to determine whether the total turn angle θtotal(n) is smaller thanthe steering switch angle θth. When the total turn angle θtotal(n) issmaller than the steering switch angle θth, the CPU determines “Yes” atthe step 1345 and then, proceeds with the process to a step 1350.

When the CPU proceeds with the process to the step 1350, the CPUexecutes a routine shown by a flowchart in FIG. 14. Therefore, when theCPU proceeds with the process to the step 1350, the CPU starts a processfrom a step 1400 of FIG. 14 and then, sequentially executes processes ofsteps 1405 and 1410 described below. Thereafter, the CPU proceeds withthe process to a step 1415.

Step 1405: The CPU calculates the smoothed yaw rate change amount ΔYs(n)in accordance with any of the expressions (24) and (25) described aboveand stores the thus-calculated smoothed yaw rate change amount ΔYs(n) inthe RAM.

Step 1410: The CPU calculates the converted value ΔYsc(n) by convertingthe smoothed yaw rate change amount ΔYs(n) in accordance with any of theexpressions (26) to (28) and stores the thus-calculated converted valueΔYsc(n) in the RAM.

When the CPU proceeds with the process to the step 1415, the CPUdetermines whether the converted value ΔYsc(n) is larger than zero. Whenthe converted value ΔYsc(n) is larger than zero, the CPU determines“Yes” at the step 1415 and then, sequentially executes processes ofsteps 1420 and 1425 described below. Thereafter, the CPU proceeds withthe process to a step 1430.

Step 1420: The CPU calculates the required time Treq(n) predictivelyrequired for the own vehicle V to turn by the steering switch remainingangle Δθ(n) (=θth−θtotal(n)) presuming that the smoothed yaw rate Ys(n)continues to increase at the rate of the converted value ΔYsc(n) inaccordance with the expression (32) and stores the thus-calculatedrequired time Treq(n) in the RAM.

Step 1425: The CPU calculates the estimated yaw rate Yest(n) by dividingthe steering switch remaining angle Δθ(n) by the required time Treq(n)in accordance with the expression (33) and stores the thus-calculatedestimated yaw rate Yest(n) in the RAM.

When the CPU proceeds with the process to the step 1430, the CPUdetermines whether the estimated yaw rate Yest(n) is larger than thestraight moving threshold Y0 (=10⁻⁶). When the estimated yaw rateYest(n) is larger than the straight moving threshold Y0, the CPUdetermines “Yes” at the step 1430 and then, sequentially executesprocesses of steps 1435 and 1440 described below. Thereafter, the CPUproceeds with the process to the step 1395 of FIG. 13 via a step 1495 toterminate this routine once.

Step 1435: The CPU calculates the first estimated turn radius Rest1(n)by dividing the vehicle speed SPD(n) by the estimated yaw rate Yest(n)as shown by the expression (34) and stores the thus-calculated firstestimated turn radius Rest1(n) in the RAM.

Step 1440: The CPU sets the first estimated turn radius Rest1(n) as theturn radius R(n) and stores the thus-set turn radius R(n) in the RAM.

On the other hand, when the estimated yaw rate Yest(n) is smaller thanor equal to the straight moving threshold Y0, the CPU determines “No” atthe step 1430 and then, sequentially executes processes of steps 1445and 1450 described below. Thereafter, the CPU proceeds with the processto the step 1395 of FIG. 13 via the step 1495 to terminate this routineonce.

Step 1445: The CPU sets the straight line equivalent value Rc (=12700 m)as the first estimated turn radius Rest1(n) as shown by the expression(35) and stores the thus-set first estimated turn radius Rest1(n) in theRAM.

Step 1450: The CPU sets the first estimated turn radius Rest1(n) as theturn radius R(n) and stores the thus-set turn radius R(n) in the RAM.

When the converted value ΔYsc(n) is zero at a time of the CPU executinga process of the step 1415, the CPU determines “No” at the step 1415 andthen, proceeds with the process to a step 1455 to determine whether thesmoothed yaw rate Ys(n) is larger than the straight moving threshold Y0.When the smoothed yaw rate Ys(n) is larger than the straight movingthreshold Y0, the CPU determines “Yes” at the step 1455 and then,executes a process of a step 1460 described below. Thereafter, the CPUproceeds with the process to the step 1395 of FIG. 13 via the step 1495to terminate this routine once.

Step 1460: The CPU sets a value calculated by dividing the vehicle speedSPD(n) by the smoothed yaw rate Ys(n) as the turn radius R(n) as shownby the expression (36) and stores the thus-set turn radius R(n) in theRAM.

On the other hand, when the smoothed yaw rate Ys(n) is smaller than orequal to the straight moving threshold Y0, the CPU determines “No” atthe step 1455 and then, executes a process of a step 1465 describedbelow. Thereafter, the CPU proceeds with the process to the step 1395 ofFIG. 13 via the step 1495 to terminate this routine once.

Step 1465: The CPU sets the straight line equivalent value Rc (=12700 m)as the turn radius R(n) as shown by the expression (37) and stores thethus-set turn radius R(n) in the RAM.

When the total turn angle θtotal(n) is larger than or equal to thesteering switch angle θth at a time of the CPU executing a process ofthe step 1345 of FIG. 13, the CPU determines “No” at the step 1345 andthen, proceeds with the process to a step 1355.

When the CPU proceeds with the process to the step 1355, the CPUexecutes a routine shown by a flowchart in FIG. 15. Therefore, when theCPU proceeds with the process to the step 1355, the CPU starts a processfrom a step 1500 of FIG. 15 and then, proceeds with the process to astep 1505 to determine whether the last-calculated converted valueΔYsc(m) among the converted values ΔYsc stored in the RAM is larger thanzero.

When the converted value ΔYsc(m) is larger than zero, the CPU determines“Yes” at the step 1505 and then, proceeds with the process to a step1510 to determine whether the last-calculated estimated yaw rate Yest(m)among the estimated yaw rates Yest stored in the RAM is larger than thestraight moving threshold Y0.

When the estimated yaw rate Yest(m) is larger than the straight movingthreshold Y0, the CPU determines “Yes” at the step 1510 and then,sequentially executes processes of steps 1515 and 1520 described below.Thereafter, the CPU proceeds with the process to the step 1395 of FIG.13 via a step 1595 to terminate this routine once.

Step 1515: The CPU calculates the second estimated turn radius Rest2(n)at the calculation cycle “n” by dividing the vehicle speed SPD(n) at thecalculation cycle “n” by the estimated yaw rate Yest(m) at thecalculation cycle “m” as shown by the expression (38) and stores thethus-calculated second estimated turn radius Rest2(n) in the RAM.

Step 1520: The CPU sets the second estimated turn radius Rest2(n) as theturn radius R(n) and stores the thus-set turn radius R(n) in the RAM.

On the other hand, when the estimated yaw rate Yest(m) at thecalculation cycle “m” is smaller than or equal to the straight movingthreshold Y0, the CPU determines “No” at the step 1510 and then,sequentially executes processes of steps 1525 and 1530 described below.

Step 1525: The CPU sets the straight line equivalent value Rc (=12700 m)as the second estimated turn radius Rest2(n) as shown by the expression(39) and stores the thus-set second estimated turn radius Rest2(n) inthe RAM.

Step 1530: The CPU sets the second estimated turn radius Rest2(n) as theturn radius R(n) and stores the thus-set turn radius R(n) in the RAM.

When the converted value ΔYsc(m) at the calculation cycle “m” at a timeof the CPU executing a process of the step 1505, the CPU determines “No”at the step 1505 and then, proceeds with the process to a step 1535 todetermine whether the smoothed yaw rate Ys(m) at the calculation cycle“m” among the smoothed yaw rates Ys stored in the RAM is larger than thestraight moving threshold Y0.

When the smoothed yaw rate Ys(m) at the calculation cycle “m” is largerthan the straight moving threshold Y0, the CPU determines “Yes” at thestep 1535 and then, sequentially executes processes of steps 1540 and1545 described below. Thereafter, the CPU proceeds with the process tothe step 1395 of FIG. 13 via the step 1595 to terminate this routineonce.

Step 1540: The CPU calculates the second estimated turn radius Rest2(n)at the calculation cycle “n” by dividing the vehicle speed SPD(n) at thecalculation cycle “n” by the smoothed yaw rate Ys(m) at the calculationcycle “m” as shown by the expression (40) and stores the thus-calculatedsecond estimated turn radius Rest2(n) in the RAM.

Step 1545: The CPU sets the second estimated turn radius Rest2(n) as theturn radius R(n) and stores the thus-set turn radius R(n) in the RAM.

On the other hand, when the smoothed yaw rate Ys(m) at the calculationcycle “m” is smaller than or equal to the straight moving threshold Y0,the CPU determines “No” at the step 1535 and then, sequentially executesprocesses of steps 1550 and 1555 described below. Thereafter, the CPUproceeds with the process to the step 1395 of FIG. 13 via the step 1595to terminate this routine once.

Step 1550 The CPU sets the straight line equivalent value Rc (=12700 m)as the second estimated turn radius Rest2(n) as shown by the expression(41) and stores the thus-set second estimated turn radius Rest2(n) inthe RAM.

Step 1555: The CPU sets the second estimated turn radius Rest2(n) as theturn radius R(n) and stores the thus-set turn radius R(n) in the RAM.

When the total turn angle θtotal(n) is larger than the turn end angleθend (=90°) at a time of the CPU executing a process of the step 1340 ofFIG. 13, the CPU determines “No” at the step 1340, that is, the CPUdetermines that the own vehicle V completes the left turning and then,executes a process of a step 1385 described below. Thereafter, the CPUproceeds with the process to the step 1395 to terminate this routineonce.

Step 1385: The CPU sets the values of the left and right turn flags XLand XR to “0”, respectively.

The concrete operation of the modified apparatus has been described.According to the modified apparatus, technical effects similar totechnical effect obtained by the first embodiment apparatus, can beobtained. Further, the modified apparatus uses the calculation methodfor calculating the turn radius R, depending on the present total turnangle θtotal of the own vehicle V and the present converted value ΔYscand determines whether the attention operation to the driver should beperformed on the basis of the predicted routes acquired on the basis ofthe turn radius R. Thus, the predicted routes approximate to the actualmoving route of the own vehicle V can be acquired, compared with a casethat the predicted routes are acquired on the basis of the presentsmoothed yaw rate Ys. As a result, the attention operation to the drivercan be appropriately performed.

Especially, when the total turn angle θtotal(n) is smaller than thesteering switch angle θth (=45°) and the converted values ΔYsc(n) islarger than zero, the modified apparatus presumes that the yaw ratecontinues to increase at a rate of a constant change amount. Then, themodified apparatus calculates the required time Treq predictivelyrequired for the own vehicle V to turn by the steering switch remainingangle Δθ(=θth−θtotal). Then, the modified apparatus calculates thepredicted routes on the basis of the estimated yaw rate Yest calculated,using the thus-calculated requested time Treq. This estimated yaw rateYest is larger than the smoothed yaw rate Ys calculated in the steeringangle increase period. Thus, the first estimated turn radius Rest1calculated, using the estimated yaw rate Yest is smaller than the turnradius R calculated, using the smoothed estimated turn radius Ys.Therefore, each of the predicted routes calculated on the basis of thefirst estimated turn radius Rest1 is approximate to the actual movingroute of the own vehicle V, compared with the predicted routescalculated on the basis of the turn radius R calculated, using thesmoothed estimated turn radius Ys. Thus, the attention operation to thedriver can be appropriately performed.

It should be noted that the process of the step 740 of FIG. 7 may beomitted. In this case, when the smoothed yaw rate Ys(n) is smaller thanor equal to the straight moving threshold Y0 before the left turn startcondition is satisfied after the left turn waiting condition issatisfied, that is, when it is determined “No” at the step 725 of FIG.7, expressions of the straight lines each extending in the vehiclemoving direction TD at the calculation cycle “n” may be calculated asthe predicted route expressions fL(n) and fR(n), respectively at thestep 1120 of FIG. 11.

Similarly, the process of the step 940 of FIG. 9 may be omitted. In thiscase, when the smoothed yaw rate Ys(n) is smaller than or equal to thestraight moving threshold Y0 before the right turn start condition issatisfied after the right turn waiting condition is satisfied, that is,when it is determined “No” at the step 925 of FIG. 9, the expressions ofthe straight lines each extending in the vehicle moving direction at thecalculation cycle “n” may be calculated as the predicted routeexpressions fL(n) and fR(n), respectively at the step 1120 of FIG. 11.

Further, the processes of the steps 1445, 1450 and 1465 of FIG. 14 maybe omitted. In this case, when the estimated yaw rate Yest(n) or thesmoothed yaw rate Ys(n) is smaller than or equal to the straight movingthreshold Y0 in the steering angle increase period, that is, when it isdetermined “No” at the steps 1430 and 1455 of FIG. 14, the expressionsof the straight lines each extending in the vehicle moving direction atthe calculation cycle “n” may be calculated as the predicted routeexpressions fL(n) and fR(n), respectively at the step 1120 of FIG. 11.

Similarly, the processes of the steps 1525, 1530, 1550 and 1555 of FIG.15 may be omitted. In this case, when the estimated yaw rate Yest(n) orthe smoothed yaw rate Ys(n) is smaller than or equal to the straightmoving threshold Y0 in the steering angle decrease period, that is, whenit is determined “No” at the steps 1510 and 1535 of FIG. 15, theexpressions of the straight lines each extending in the vehicle movingdirection at the calculation cycle “n” may be calculated as thepredicted route expressions fL(n) and fR(n), respectively at the step1120 of FIG. 11.

Second Embodiment

Below, the driving assist apparatus of the vehicle according to a secondembodiment (hereinafter, will be referred to as “the second embodimentapparatus”) will be described. The second embodiment apparatus is thesame as the first embodiment apparatus except that a method fordetermining whether there is an object to be alerted to the driver isdifferent from a method of the first embodiment apparatus.

In particular, when the straight line gL(n) expressed by the predictedroute expression g(n) of the object crosses the effective portion(s)LLep and/or LRep of the predicted route(s) of the own vehicle V at onepoint or two points which is/are the crossing point(s), the firstembodiment apparatus specifies the crossing point(s) to be determined.When the time condition is satisfied for the crossing point(s), thefirst embodiment apparatus performs the attention operation to thedriver.

On the other hand, in the second embodiment, the effective lengths LLeand LRe are not set. Therefore, each of the predicted routes of the ownvehicle V is a circle. When the straight line gL(n) crosses the circularpredicted routes of the own vehicle V at two or four points which arethe crossing points, the second embodiment apparatus specifies thecrossing point(s) to be determined among the two or four crossingpoints. When the time condition and a length condition are satisfied,regarding the crossing point(s), the second embodiment apparatusperforms the attention operation to the driver.

Therefore, the second embodiment apparatus is the same as the firstembodiment apparatus except that the second embodiment apparatusdetermines whether the straight line gL(n) crosses the circularpredicted routes of the own vehicle V and determines whether the timecondition as well as the length condition are satisfied. Accordingly,with reference to FIG. 16, an operation of the second embodimentapparatus different from the operation of the first embodiment apparatuswill be mainly described.

<Acquisition of Object Information>

Similar to the first embodiment apparatus, the second embodimentapparatus acquires the object information on the object existing aroundthe own vehicle V. In an example shown in FIG. 16, the second embodimentapparatus acquires the information on the object E to I existing aroundthe own vehicle V as the object information at the calculation cycle“n”.

<Calculation of Expression g of Object>

Similar to the first embodiment apparatus, the second embodimentapparatus calculates the predicted route expression g of the object. Inthe example shown in FIG. 16, the second embodiment apparatus calculatesthe expressions ge(n), gf(n), gg(n), gh(n) and gi(n) of the objects E toI, respectively.

<Second Crossing Condition>

Similar to the first embodiment apparatus or the modified apparatus, thesecond embodiment apparatus calculates the predicted left and right endroute expressions fL(n) and fR(n). Further, in the second embodiment, atarget area r(n) is defined between the predicted left and right endroute expressions fL(n) and fR(n). The second embodiment apparatusdetermines whether a second crossing condition is satisfied. The secondcrossing condition is a condition that the straight line gL(n) expressedby the expression g(n) crosses at least one of a circular line expressedby the predicted left end route expression fL(n) and a circular lineexpressed by the predicted right end route expression fR(n).

In the example shown in FIG. 16, the straight line geL(n) expressed bythe expression ge(n) crosses the predicted left end route at points E1and E4 and the predicted right end route at points E2 and E3. Thus, theexpression ge(n) satisfies the second crossing condition.

The straight line gfL(n) expressed by the expression gf(n) crosses thepredicted left end route at points F1 and F4 and the predicted right endroute at points F2 and F3. Thus, the expression gf(n) satisfies thesecond crossing condition.

The straight line ggL(n) expressed by the expression gg(n) crosses thepredicted left end route at a point G2 and the predicted right end routeat a point G1. Thus, the expression gg(n) satisfies the second crossingcondition.

The straight line ghL(n) expressed by the expression gh(n) crosses thepredicted left end route at points H1 and H2. Thus, the expression gh(n)satisfies the second crossing condition.

On the other hand, the straight line giL(n) expressed by the expressiongi(n) does not cross the predicted left and right end routes. Thus, theexpression gi(n) does not satisfy the second crossing condition.

<Calculation of Coordinates of Crossing Point(s)>

When the expression g(n) satisfies the second crossing condition, thesecond embodiment apparatus calculates the number of the points wherethe straight line gL(n) expressed by the expression g(n) crosses thepredicted left and/or right end route(s). Hereinafter, the point wherethe straight line gL(n) expressed by the expression g(n) crosses thepredicted left or right end route will be referred to as “the secondcrossing point”.

When the number of the second crossing points is four, the secondembodiment apparatus calculates, as coordinates of crossing point Q1(n),coordinates of a point where the straight line gL(n) expressed by theexpression g(n) enters from the outside of the target area r(n) into thetarget area r(n) in the moving direction of the object and the straightline gL(n) expressed by the expression g(n) crosses the predicted leftor right end route. Further, the second embodiment apparatus calculates,as coordinates of crossing point Q2(n), coordinates of a point where thestraight line gL(n) expressed by the expression g(n) enters from theoutside of the target area r(n) into the target area r(n) in the movingdirection of the object and the straight line gL(n) expressed by theexpression g(n) crosses the predicted left or right end route.Therefore, the crossing point Q1(n) is the first crossing point in themoving direction of the object and the crossing point Q2(n) is the thirdcrossing point in the moving direction of the object.

In the example shown in FIG. 16, regarding the expression ge(n), thesecond crossing points are points E1 to E4 and thus, the number of thesecond crossing points is four. Therefore, the second embodimentapparatus calculates coordinates of the point E1 as coordinates ofcrossing point Q1 e(n) and coordinates of the point E3 as coordinates ofcrossing point Q2 e(n). The point E1 is a point where the straight linegeL(n) expressed by the expression ge(n) enters from the outside of thetarget area r(n) into the target area r(n) in the moving direction ofthe object E, that is, in a downward direction on a paper of FIG. 16 andthe straight line geL(n) expressed by the expression ge(n) crosses thepredicted left end route. The point E3 is a point where the straightline geL(n) expressed by the expression ge(n) enters from the outside ofthe target area r(n) into the target area r(n) in the moving directionof the object E, that is, in the downward direction on the paper of FIG.16 and the straight line geL(n) expressed by the expression ge(n)crosses the predicted right end route.

Also, regarding the expression gf(n), the second crossing points arepoints F1 to F4 and thus, the number of the second crossing points isfour. Therefore, the second embodiment apparatus calculates coordinatesof the point F1 as coordinates of crossing point Q1 f(n) and coordinatesof the point F3 as coordinates of crossing point Q2 f(n), The point F1is a point where the straight line gfL(n) expressed by the expressiongf(n) enters from the outside of the target area r(n) into the targetarea r(n) in the moving direction of the object F, that is, in an upwarddirection on the paper of FIG. 16 and the straight line gfL(n) expressedby the expression gf(n) crosses the predicted left end route. The pointF3 is a point where the straight line gfL(n) expressed by the expressiongf(n) enters from the outside of the target area r(n) into the targetarea r(n) in the moving direction of the object E, that is, in theupward direction on the paper of FIG. 16 and the straight line gfL(n)expressed by the expression gf(n) crosses the predicted right end route.

When the number of the second crossing points is two, the secondembodiment apparatus calculates, as coordinates of crossing point Q(n),coordinates of a point where the straight line gL(n) expressed by theexpression g(n) enters from the outside of the target area r(n) into thetarget area r(n) in the moving direction of the, object and the straightline gL(n) expressed by the expression g(n) crosses the predicted leftor right end route. Therefore, the crossing point Q(n) is the firstcrossing point in the moving direction of the object.

In the example shown in FIG. 16, regarding the expression gg(n), thesecond crossing points are points G1 and G2 and thus, the number of thesecond crossing points is two. Therefore, the second embodimentapparatus calculates coordinates of the point G1 as coordinates ofcrossing point Qg(n). The point G1 is a point where the straight lineggL(n) expressed by the expression gg(n) enters from the outside of thetarget area r(n) into the target area r(n) in the moving direction ofthe object E, that is, in a leftward direction on the paper of FIG. 16and the straight line ggL(n) expressed by the expression gg(n) crossesthe predicted right end route.

Also, regarding the expression gh(n), the second crossing points arepoints H1 and H2 and thus, the number of the second crossing points istwo. Therefore, the second embodiment apparatus calculates coordinatesof the point H1 as coordinates of crossing point Qh(n). The point H1 isa point where the straight line ghL(n) expressed by the expression gh(n)enters from the outside of the target area r(n) into the target arear(n) in the moving direction of the object H, that is, in the leftwarddirection on the paper of FIG. 16 and the straight line ghL(n) expressedby the expression gh(n) crosses the predicted left end route.

When the crossing points Q1(n), Q2(n) and Q(n) are located on thepredicted left end route, the lengths of the arc of the predicted leftend route from the vehicle left end OL(n) to the crossing points Q1(n),Q2(n) and Q(n) in the turning direction of the own vehicle V will bereferred to as “the lengths LL1(n), LL2(n) and LL(n)”, respectively.

When the crossing points Q1(n), Q2(n) and Q(n) are located on thepredicted right end route, the lengths of the arc of the predicted rightend route from the vehicle right end OR(n) to the crossing points Q1(n),Q2(n) and O(n) in the turning direction of the own vehicle V will bereferred to as “the lengths LR1(n), LR2(n) and LR(n)”, respectively.

For example, the length LL1(n) is calculated by multiplying the left endturn radius RL(n) by an angle defined by a vector directed from the turncenter coordinates (Cx(n), Cy(n)) toward the crossing point Q1(n) and avector directed from the turn center coordinates (Cx(n), Cy(n)) towardthe position O(n) of the own vehicle V. The remaining lengths LL2(n),LL(n), LR1(n), LR2(n) and LR(n) are calculated by the similar method,

<Setting of Target Crossing Point(s)>

When the number of the set second crossing points is two and thus, thesecond embodiment apparatus calculates the coordinates of the crossingpoint Q1(n) and the coordinates of the crossing point Q2(n), the secondembodiment apparatus compares the length of the arc of the predictedright or left end route from the vehicle right or left end OR(n) orOL(n) to the crossing point Q1(n) in the turning direction of the ownvehicle V with the length of the arc of the predicted right or left endroute from the vehicle right or left end OR(n) or OL(n) to the crossingpoint Q2(n) in the turning direction of the own vehicle V. The secondembodiment apparatus sets the crossing point corresponding to theshorter length as the target crossing point Qt(n). Below, this will bedescribed in detail.

When the own vehicle V turns right, the crossing point Q1(n) such as thecrossing point Q1 e(n) in FIG. 16 is located on the predicted left endroute and the crossing point Q2(n) such as the crossing point Q2 e(n) inFIG. 16 is located on the predicted right end route. Therefore, thesecond embodiment apparatus calculates the length LL1(n) of the arc ofthe predicted left end route from the vehicle left end OL(n) to thecrossing point Q1(n) such as the crossing point Q1 e(n) in FIG. 16 inthe turning direction of the own vehicle V and the length LR2(n) of thearc of the predicted right end route from the vehicle right end OR(n) tothe crossing point Q2(n) such as the crossing point Q2 e(n) in FIG. 16in the turning direction of the own vehicle V. Then, the secondembodiment apparatus compares the length LL1(n) with the length LR2(n).The second embodiment apparatus sets the crossing point such as thecrossing point Q1 e(n) in FIG. 16 corresponding to the shorter length asthe target crossing point Qt(n).

Similarly, when the own vehicle V turns left, the crossing point Q1(n)is located on the predicted right end route and the crossing point Q2(n)is located on the predicted left end route. Therefore, the secondembodiment apparatus calculates the length LR1(n) of the arc of thepredicted right end route from the vehicle right end OR(n) to thecrossing point Q1(n) in the turning direction of the own vehicle V andthe length LL2(n) of the arc of the predicted left end route from thevehicle left end OL(n) to the crossing point Q2(n) in the turningdirection of the own vehicle V. Then, the second embodiment apparatuscompares the length LR1(n) with the length LL2(n). The second embodimentapparatus sets the crossing point corresponding to the shorter length asthe target crossing point Qt(n).

In the example shown in FIG. 16, the own vehicle V turns right. Thus,regarding the expression ge(n), the crossing point Q1 e(n) is located onthe predicted left end route and the crossing point Q2 e(n) is locatedon the predicted right end route. Therefore, the second embodimentapparatus calculates the length LL1 e(n) of the arc of the predictedleft end route from the vehicle left end OL(n) to the crossing point Q1e(n) in the turning direction of the own vehicle V and the length LR2e(n) of the arc of the predicted right end route from the vehicle rightend OR(n) to the crossing point Q2 e(n) in the turning direction of theown vehicle V. Then, the second embodiment apparatus compares the lengthLL1 e(n) with the length LR2 e(n). The length LL1 e(n) is shorter thanthe length LR2 e(n) and thus, the second embodiment apparatus sets thecrossing point Q1 e(n) as the target crossing point Qt(n).

Also, regarding the expression gf(n), the crossing point Q1 f(n) islocated on the predicted left end route and the crossing point Q2 f(n)is located on the predicted right end route. Therefore, the secondembodiment apparatus calculates the length LL1 f(n) of the arc of thepredicted left end route from the vehicle left end OL(n) to the crossingpoint Q1 f(n) in the turning direction of the own vehicle V and thelength LR2 f(n) of the arc of the predicted right end route from thevehicle right end OR(n) to the crossing point Q2 f(n) in the turningdirection of the own vehicle V. Then, the second embodiment apparatuscompares the length LL1 f(n) with the length LR2 f(n). The length LR2f(n) is shorter than the length LL1 f(n) and thus, the second embodimentapparatus sets the crossing point Q2 f(n) as the target crossing pointQt(n).

Hereinafter, when the target crossing point Qt(n) is located on thepredicted left end route, the length of the arc of the predicted leftend route from the vehicle left end OL(n) to the target crossing pointQt(n) in the turning direction of the own vehicle V will be referred toas “the length LLt(n)”. When the target crossing point Qt(n) is locatedon the predicted right end route, the length of the arc of the predictedright end route from the vehicle right end OR(n) to the target crossingpoint Qt(n) in the turning direction of the own vehicle V will bereferred to as “the length LRt(n)”.

<Calculation of Second Time>

The second embodiment apparatus calculates a time predicted for theobject to reach the predicted route as a second time t2 for determiningwhether the time condition is satisfied. In particular, when thestraight line gL(n) expressed by the expression g(n) crosses thepredicted left or right end route at the target crossing point Qt(n) orthe crossing point Q(n), the second embodiment apparatus calculates thesecond time t2(n) predicted for the object corresponding to the straightline gL(n) expressed by the expression g(n) to reach the target crossingpoint Qt(n) or the crossing point Q(n). The second time t2(n) iscalculated by dividing the length of the straight line from the positionof the object to the target crossing point Qt(n) or the crossing pointQ(n) by a moving speed v(n) of the object.

In the example shown in FIG. 16, the second embodiment apparatuscalculates the second time t2e(n) predicted for the object E to reachthe target crossing point Qte(n), the second time t2f(n) predicted forthe object F to reach the target crossing point Qtf(n), the second timet2g(n) predicted for the object G to reach the crossing point Qg(n) andthe second time t2h(n) predicted for the object H to reach the crossingpoint Qh(n).

<Time Condition and Length Condition>

The second embodiment apparatus determines whether the time conditionthat the second time t2(n) is smaller than or equal to a predeterminedsecond time t2th, is satisfied. In the second embodiment, thepredetermined second time t2th is 4 seconds. When the time condition issatisfied, regarding any of the expressions g(n), the second embodimentapparatus determines that the object may cross the predicted route ofthe own vehicle V within the predetermined second time t2th.

When the second embodiment apparatus calculates the coordinates of thetarget crossing point Qt(n) located on the predicted left end route, thesecond embodiment apparatus determines whether a point where the objectcrosses the predicted route of the own vehicle V, is located in theportion of the predicted route corresponding to the effective lengthLLe(n) by determining whether a length condition shown by an inequalityexpression (42) described below is satisfied. When the second embodimentapparatus calculates the coordinates of the target crossing point Qt(n)located on the predicted right end route, the second embodimentapparatus determines whether the point where the object crosses thepredicted route of the own vehicle V, is located in the portion of thepredicted route corresponding to the effective length LRe(n) bydetermining whether a length condition shown by an inequality expression(43) described below is satisfied.LLt(n)≤LLe(n)  (42)LRt(n)≤LRe(n)  (43)

When the second embodiment apparatus calculates the coordinates of thecrossing point Q(n) located on the predicted left end route, the secondembodiment apparatus determines whether a point where the object crossesthe predicted route of the own vehicle V, is located in the portion ofthe predicted route corresponding to the effective length LLe(n) bydetermining whether a length condition shown by an inequality expression(44) described below is satisfied. When the second embodiment apparatuscalculates the coordinates of the crossing point Q(n) located on thepredicted right end route, the second embodiment apparatus determineswhether the point where the object crosses the predicted route of theown vehicle V, is located in the portion of the predicted routecorresponding to the effective length LRe(n) by determining whether alength condition shown by an inequality expression (45) described belowis satisfied.LL(n)≤LLe(n)  (44)LR(n)≤LRe(n)  (45)

When any of the length conditions is satisfied, regarding any of theexpressions g(n), the second embodiment apparatus determines that thepoint where the object crosses the predicted route, is located in theportion of the predicted route corresponding to the effective length,that is, there is the target object. On the other hand, when the lengthconditions are not satisfied, regarding the expressions g(n), the secondembodiment apparatus determines that the point where the object crossesthe predicted route, is not located in the portion of the predictedroute corresponding to the effective length, that is, there is no targetobject.

In the example shown in FIG. 16, assuming that the second time t2e(n) is1 second, the second time t2f(n) is 4 seconds, the second time t2g(n) is3 seconds and the second time t2h(n) is 2 seconds, the time condition issatisfied, regarding the expressions ge(n), gf(n), gg(n) and gh(n).Thus, the second embodiment apparatus determines whether the lengthcondition is satisfied, regarding the expressions ge(n), gf(n), gg(n)and gh(n).

Regarding the expression ge(n), the target crossing point Qte(n) iscalculated and this target crossing point Qte(n) is located on thepredicted left end route. Thus, the second embodiment apparatusdetermines whether the length condition shown by the inequalityexpression (42) is satisfied. As apparent from the FIG. 16, the lengthLLte(n) is shorter than the effective left end length LLe(n) and thus,the length condition shown by the inequality expression (42) issatisfied.

Regarding the expression gf(n), the target crossing point Qtf(n) iscalculated and this target crossing point Qtf(n) is located on thepredicted right end route. Thus, the second embodiment apparatusdetermines whether the length condition shown by the inequalityexpression (43) is satisfied. As apparent from the FIG. 16, the lengthLRtf(n) is shorter than the effective right end length LRe(n) and thus,the length condition shown by the inequality expression (43) issatisfied.

Regarding the expression gg(n), the crossing point Qg(n) is calculatedand this crossing point Qg(n) is located on the predicted right endroute. Thus, the second embodiment apparatus determines whether thelength condition shown by the inequality expression (45) is satisfied.As apparent from the FIG. 16, the length LRg(n) is longer than theeffective right end length LRe(n) and thus, the length condition shownby the inequality expression (45) is not satisfied.

Regarding the expression gh(n), the crossing point Qh(n) is calculatedand this crossing point Qh(n) is located on the predicted left endroute. Thus, the second embodiment apparatus determines whether thelength condition shown by the inequality expression (44) is satisfied.As apparent from the FIG. 16, the length LLh(n) is longer than theeffective left end length LLe(n) and thus, the length condition shown bythe inequality expression (44) is not satisfied.

As described above, the time condition and the length condition aresatisfied, regarding the expressions ge(n) and gf(n). Thus, the secondembodiment apparatus determines that there are the target objects suchas the objects E and F.

In the example shown in FIG. 16, assuming that the second time t2e(n) is5 seconds, the second time t2f(n) is 10 seconds, the second time t2g(n)is 3 seconds and the second time t2h(n) is 2 seconds, the time conditionis satisfied, regarding the expressions gg(n) and gh(n). Thus, thesecond embodiment apparatus determines whether the length condition issatisfied, regarding the expressions gg(n) and gh(n). As describedabove, the length condition is not satisfied, regarding the expressionsgg(n) and gh(n). Thus, the second embodiment apparatus determines thatthere is no target object.

<Attention Operation to Driver>

Similar to the first embodiment apparatus, the second embodimentapparatus performs the attention operation to the driver when the secondembodiment apparatus determines that there is the target object. On theother hand, when the second embodiment apparatus determines that thereis no target object, the second embodiment apparatus does not performthe attention operation to the driver.

<Concrete Operation of Second Embodiment Apparatus>

Below, the concrete operation of the second embodiment apparatus will bedescribed. The CPU of the driving assist ECU 10 of the second embodimentapparatus executes a routine shown by a flowchart in FIG. 17 when theCPU proceeds with the process to the step 1130 of FIG. 11. The routineshown in FIG. 17 will be described in case that the object informationon one object is acquired. In this regard, in case that the objectinformation on the objects is acquired, the routine shown in FIG. 17 isexecuted for the object information on each of the objects. When the CPUproceeds with the process to the step 1130 of FIG. 11, the CPU starts aprocess from a step 1700 of FIG. 17 and then, sequentially executesprocesses of steps 1705 and 1710 described below. Thereafter, the CPUproceeds with the process to a step 1715.

Step 1705: The CPU acquires information on the object existing aroundthe own vehicle V as the object information at the calculation cycle “n”as described above and stores the thus-acquired object information inthe RAM of the driving assist ECU 10.

Step 1710: The CPU calculates the predicted route expression g(n) of theobject at the calculation cycle “n” on the basis of the objectinformation and stores the thus-calculated predicted route expressiong(n) in the RAM.

When the CPU proceeds with the process to the step 1715, the CPUdetermines whether the predicted route expression g(n) of the objectsatisfies the second crossing condition. When the predicted routeexpression g(n) of the object satisfies the second crossing condition,the CPU determines “Yes” at the step 1715 and then, executes a processof a step 1720 described below. Thereafter, the CPU proceeds with theprocess to a step 1725.

Step 1720: The CPU calculates the coordinates of the crossing pointQ1(n) and the coordinates of the crossing point Q2(n) and stores thethus-calculated coordinates in the RAM as described above when thestraight line gL(n) expressed by the expression g(n) crosses thepredicted left and right end routes at the four crossing points. Whenthe straight line gL(n) expressed by the expression g(n) crosses thepredicted left end route and/or the predicted right end route at the twocrossing points, the CPU calculates the coordinates of the crossingpoint Q(n) and stores the thus-calculated coordinates in the RAM.

When the CPU proceeds with the process to the step 1725, the CPUdetermines whether the number of the crossing points Q(n) is two. Whenthe number of the crossing points Q(n) is two, that is, when thecoordinates of the crossing points Q1(n) and Q2(n) are calculated, theCPU determines “Yes” at the step 1725 and then, sequentially executesprocesses of steps 1730 and 1735 described below. When the number of thecrossing point Q(n) is one, that is, when the coordinates of thecrossing point Q(n) are calculated, the CPU determines “No” at the step1725 and then, executes the process of the step 1735.

Step 1730: The CPU sets any of the crossing points Q1(n) and Q2(n) asthe target crossing point Qt(n) as described above. The CPU stores thecoordinates of any of the crossing points Q1(n) and Q2(n) set as thetarget crossing point Qt(n) in the RAM.

Step 1735: The CPU calculates the second time t2(n) predicted for theobject to reach the crossing point Qt(n) or Q(n) as described above andstores the thus-calculated second time t2(n) in the RAM.

Then, the CPU proceeds with the process to a step 1740. When the CPUproceeds with the process to the step 1740, the CPU determines whetherthe second time t2(n) satisfies the time condition (i.e., t2(n)≤t2th (=4seconds)). When the second time t2(n) satisfies the time condition, theCPU determines “Yes” at the step 1740 and then, proceeds with theprocess to a step 1745.

When the CPU proceeds with the process to the step 1745, the CPUdetermines whether any of the length conditions shown by the inequalityexpressions (42) to (45) is satisfied. When any of the length conditionsis satisfied, the CPU determines “Yes” at the step 1745, that is, thereis the target object and then, executes a process of a step 1750.Thereafter, the CPU proceeds with the process to the step 1195 of FIG.11 via a step 1795 to terminate this routine once.

Step 1750: The CPU sends a request signal for performing the attentionoperation to the driver to the CPUs of the display ECU 20 and the alertECU 30. Thereby, the display device 21 and the buzzer 31 perform theattention operation.

On the other hand, when the predicted route expression g(n) of theobject does not satisfy the second crossing condition at a time of theCPU executing a process of the step 1715, the CPU determines “No” at thestep 1715, that is, there is no target object and then, proceeds withthe process to the step 1195 of FIG. 11 via the step 1795 to terminatethis routine once.

When the second time t2(n) does not satisfy the time condition at a timeof the CPU executing a process of the step 1740, the CPU determines “No”at the step 1740, that is, there is no target object and then, proceedswith the process to the step 1195 of FIG. 11 via the step 1795 toterminate this routine once.

When the length condition is not satisfied at a time of the CPUexecuting a process of the step 1745, the CPU determines “No” at thestep 1745, that is, there is no target object and then, proceeds withthe process to the step 1195 of FIG. 11 via the 1795 to terminate thisroutine once.

The concrete operation of the second embodiment apparatus has beendescribed. According to the second embodiment apparatus, the technicaleffects similar to the technical effects obtained by the firstembodiment apparatus, can be obtained.

The second embodiment apparatus uses the same method for calculating theturn radius R as the method used by the first embodiment apparatus. Inthis regard, the second embodiment apparatus may use the same method forcalculating the turn radius R as the method used by the modifiedapparatus.

The driving assist apparatuses according to the embodiments and themodified example of the invention have been described. It should benoted that the present invention is not limited to the aforementionedembodiments and various modifications can be employed within the scopeof the invention.

For example, the first and second embodiment apparatuses and themodified apparatus (hereinafter, these apparatuses will be collectivelyreferred to as “the first embodiment apparatus and the like”) may beconfigured to estimate one predicted route or three or more predictedroutes in place of acquiring two predicted routes such as the predictedleft and right end routes. The predicted routes are not limited to theroutes predicted for the vehicle left and right end OL and OR to pass,that is, the predicted left and right end routes. For example, thepredicted route may be a route predicted for the vehicle base point O topass. In this case, the vehicle base point O is not limited to a centerpoint between the vehicle left and right ends OL and OR and may be apoint at a center of the front end portion of the own vehicle V in thevehicle width direction.

Further, the first embodiment apparatus and the like may be configuredto perform the attention operation to the driver when the own vehicle Vturns left or right at an area where the own vehicle V can turn such asa parking of the building and a road next to an entrance of the parkingin addition to when the own vehicle V turns left or right at theintersection.

Further, the first embodiment apparatus and the like may comprise a GNSSreceiver and store a map information in the memory thereof. Further, thefirst embodiment apparatus and the like may be configured to determinewhether the own vehicle V is in the area where the own vehicle V canturn (hereinafter, will be referred to as “the turning area”) by theself-position estimation using the GNSS. When the first embodimentapparatus and the like determines that the own vehicle V is in theturning area, the first embodiment apparatus and the like may beconfigured to calculate the turn end angle bend for calculating theremaining turn angle θre for each turning area on the basis of the shapeof the turning area described in the map information. In this case, thefirst embodiment apparatus and the like may be configured to determinewhether the own vehicle V is in the turning area by the method describedfor the first embodiment apparatus and the like at an area where theself-position estimation using the GNSS cannot be performed and may beconfigured to set the turn end angle θend to 90°.

Further, the first embodiment apparatus and the like may comprise anin-vehicle device which can communicate with a roadside device installedin the turning area. In this case, the first embodiment apparatus andthe like may be configured to determine whether the own vehicle V is inthe turning area by the wireless communication with the roadside device.When the first embodiment apparatus and the like determines that the ownvehicle V is in the turning area, the first embodiment apparatus and thelike may be configured to calculate the turn end angle θend forcalculating the remaining turn angle θre for each turning area. In thiscase, the first embodiment apparatus and the like may be configured todetermine whether the own vehicle V is in the turning area by the methoddescribed for the first embodiment apparatus and the like at the areawhere the self-position estimation using the wireless communicationcannot be performed and may be configured to set the turn end angle θendto 90°.

Further, the first embodiment apparatus and the like may be configuredto determine that the left turn waiting condition is satisfied when thefirst embodiment apparatus and the like uses one of the conditions LW1to LW3 as the condition for determining whether the left turn waitingcondition is satisfied and the condition LW1 or LW2 or LW3 is satisfiedor when the first embodiment apparatus and the like uses two of theconditions LW1 to LW3 as the condition for determining whether the leftturn waiting condition is satisfied and the two of the conditions LW1 toLW3 are satisfied.

Further, the first embodiment apparatus and the like may be configuredto determine that the right turn waiting condition is satisfied when thefirst embodiment apparatus and the like uses one of the conditions RW1to RW3 as the condition for determining whether the right turn waitingcondition is satisfied and the condition RW1 or RW2 or RW3 is satisfiedor when the first embodiment apparatus and the like uses two of theconditions RW1 to RW3 as the condition for determining whether the rightturn waiting condition is satisfied and the two of the conditions RW1 toRW3 are satisfied.

Further, the first embodiment apparatus and the like may be configuredto determine that the left turn start condition is satisfied when thefirst embodiment apparatus and the like uses one of the conditions LS1to LS6 as the condition for determining whether the left turn startcondition is satisfied and the one of the condition LS1 to LS6 issatisfied or when the first embodiment apparatus and the like uses twoto five of the conditions LS1 to LS6 as the condition for determiningwhether the left turn start condition is satisfied and the two to fiveof the conditions LS1 to LS6 are satisfied.

Further, the first embodiment apparatus and the like may be configuredto determine that the right turn start condition is satisfied when thefirst embodiment apparatus and the like uses one of the conditions RS1to RS6 as the condition for determining whether the right turn startcondition is satisfied and the one of the condition RS1 to RS6 issatisfied or when the first embodiment apparatus and the like uses twoto five of the conditions RS1 to RS6 as the condition for determiningwhether the right turn start condition is satisfied and the two to fiveof the conditions RS1 to RS6 are satisfied.

Further, the first embodiment apparatus and the like may be configuredto use the yaw rate Y estimated from the lateral acceleration Gy and thevehicle speed SPD or the yaw rate Y estimated from the steering angleθsw and the vehicle speed SPD in place of the yaw rate Y detected by theyaw rate sensor 17.

Further, the first embodiment apparatus and the like may be configuredto determine whether the own vehicle V completes the left or rightturning only when the state of each of the left direction blinkers orthe state of each of the right direction blinkers changes from theblinking state to the non-blinking state without determining whether thetotal turn angle θtotal is larger than the turn end angle θend fordetermining whether the own vehicle V completes the left or rightturning.

Further, the first embodiment apparatus and the like may be configuredto acquire the object information, using a camera or the roadside devicein place of the front radar sensors 16L and 16R.

Further, the first embodiment apparatus and the like may be applied tothe vehicle which moves on the left side of the road as well as thevehicle which moves on the right side of the road.

What is claimed is:
 1. A driving assist apparatus of a vehicle driven bya driver, comprising: at least one sensor to detect a moving objectexisting around the vehicle; and an electronic control unit to performan attention operation to the driver of the vehicle by being configuredto: set two predicted moving routes for two end sides of the vehicle,the two predicted moving routes having different radii, each of the twopredicted moving routes being set such that: when the driver turns thevehicle left: after the driver has started to turn the vehicle left:calculate a curvature radius of a first moving route of the vehiclebased on an operation made by the driver to turn the vehicle left;calculate a change rate of a yaw rate of the vehicle based on yaw rateinformation detected by a yaw rate sensor of the vehicle; identify aspecific point in the first moving route where the curvature radius ofthe first moving route is predicted to become smallest using the changerate of the yaw rate of the vehicle, based on a presumption that thecurvature radius of the first moving route decreases when the yaw rateof the vehicle increases by the change rate of the yaw rate on amoment-to-moment basis while the vehicle turns left; set, as a predictedminimum left turn radius, the curvature radius at the identifiedspecific point in the first moving route; and set a route curved alongan arc having the predicted minimum left turn radius as the predictedmoving route; and when the driver turns the vehicle right: after thedriver has started to turn the vehicle right: calculate a curvatureradius of a second moving route of the vehicle based on an operationmade by the driver to turn the vehicle right; calculate the change rateof the yaw rate of the vehicle; identify a specific point in the secondmoving route where the curvature radius of the second moving route ispredicted to become smallest using the change rate of the yaw rate ofthe vehicle, based on a presumption that the curvature radius of thesecond moving route decreases when the yaw rate of the vehicle increasesby the change rate of the yaw rate on a moment-to-moment basis while thevehicle turns right; set, as a predicted minimum right turn radius, thecurvature radius at the identified specific point in the second movingroute; and set a route curved along an arc having the predicted minimumright turn radius as the predicted moving route; and perform theattention operation when a time predicted for the vehicle to reach apoint where the moving object crosses at least one of the two predictedmoving routes is smaller than or equal to a threshold time.
 2. Thedriving assist apparatus of the vehicle as set forth in claim 1,wherein: the vehicle comprises at least one left direction blinkeractivated for indicating that the vehicle is to turn left and at leastone right direction blinker activated for indicating that the vehicle isto turn right; and the electronic control unit is configured to: predictthat the vehicle turns left when a speed of the vehicle is within apredetermined speed range and the left direction blinker is activated;and predict that the vehicle turns right when the speed of the vehicleis within the predetermined speed range and the right direction blinkeris activated.
 3. The driving assist apparatus of the vehicle as setforth in claim 1, wherein: the vehicle comprises at least one leftdirection blinker activated for indicating that the vehicle is to turnleft and at least one right direction blinker activated for indicatingthat the vehicle is to turn right; and the electronic control unit isconfigured to determine whether the vehicle turns left or right based ona vehicle information including activation states of the left and rightdirection blinkers.
 4. The driving assist apparatus of the vehicle asset forth in claim 3, wherein the vehicle information includes at leastone of the yaw rate of the vehicle, a speed of the vehicle, alongitudinal acceleration of the vehicle, an operation amount of anacceleration pedal of the vehicle, a lateral acceleration of the vehicleand a steering angle of a steering wheel of the vehicle.
 5. The drivingassist apparatus of the vehicle as set forth in claim 1, wherein theelectronic control unit is configured to: calculate the curvature radiusof the first moving route and the curvature radius of the second movingroute, according to different preset ways based on a result ofdetermination as to whether a smoothed yaw rate of the vehicle is largerthan a preset threshold.